This is a reprint of my /r/DnDBehindtheScreen article published on 12 June 2017.

02/29/20: All Homebrewery links have been updated to be GMBinder links. I have reorganized text to minimize text spillage at most levels of zoom. The section under Out of Turn Effects has been entirely rewritten.

Halloa folks. Four score and seven years ago, I wrote a spiel about enabling Big Bad Solos (BBSs) to stand up to a group of PCs without also demolishing the PCs called Designing the Mechanics of the Big Bad Now that the Union has succeeded in remaining intact, I have finally sat my big butt down onto a big red couch and quilled the following Big Bad Solo Monster Inserts. What do I mean by “Inserts”? I mean you take these features and insert them into monsters to transform them into Big Bad Solos.

Cheat Sheet: Website Page; GMBinder Link; Google Drive Pdf Link. This document carries all of the inserts and example monsters with none of the explanation. If you want just the monsters, scroll to the bottom of this page. If you want a greater understanding of these features, continue reading. As of February 29th, 2020, these links contain significant revisions (colored in blue).

Momentarily, I will describe the following:

The following inserts are intended to be added to monsters to transform them from lean to mean, running to cunning, and 2-round-offenders to 6-round-tormenters. These inserts incorporate three broad categories of Big Bad Solo creatures: The Rough, The Quick, and The Sublime.

1) The Rough tend to let their muscles do the talking and, if they do deign to talk, it’s often through beastly grunts and snarls. They tend to be bigger and fall harder. Watch out for them falling on top of you; that may be their signature move.

2) The Quick tend to strike fast and often. They move like the wind and are difficult to catch. They tend to be smaller and hard to find. That’s what she said.

3) The Sublime are the magic-using-centric creatures; let’s not confuse ourselves by trying to force clever wordplay. But then why the word “sublime” and not “magical”? Cuz I like the way “sublime” sounds; please leave me my petty eccentricities. Anyways, it’s annoying, monologuing, tangenting turkey-jerks like me that strive to reshape reality (and DnD mechanics) to their liking. Such folks fit the bill for these eldritch Big Bads.

These inserts will depict 5 types of features that fit into each of these 3 categories of BBS creatures. The feature types are as follows: A) Damage Mitigation, B) Condition Mitigation, C) Mobility, D) Forced Movement Capability, and E) Out of Turn Effects. They are ordered in no particular order of significance. Most inserts will contain a combination of a couple or several of these 5 types. I will make a brief note about each’s significance before providing the inserts themselves; you can find a fuller explanation for each in my aforementioned article, Designing the Mechanics of the Big Bad.

Finally, the use of these inserts assumes that you are utilizing some combination of the AngryGM’s Paragon Monster Features. This wonderful set of mechanics created by AngryGM, which include Paragon Fortitude, Paragon Exhaustion and Paragon Fury, creates a baseline upon which truly dynamic BBSs can be built. If you don’t want to read the article itself to understand the conceptual logic behind it, then here’s what the mechanics simply are (copied and pasted from the article):

Paragon Fortitude. The creature has multiple pools of hit points, each of which is tracked separately. All damage and healing must be completely applied to only one pool. When a pool is reduced to zero, all ongoing conditions and effects affecting the creature end. Once a pool is reduced to zero, that pool cannot receive any healing until after a long rest. If all hit point pools are reduced to zero, the creature is killed.

Paragon Exhaustion. The creature may take one complete turn in each round of combat for each hit point pool it has above zero and receives one reaction between each of its turns. When a pool of hit points has been reduced to zero, the creature loses one turn each round thereafter. The creature determines initiative normally for its first turn, though it gains advantage on the roll. Each subsequent turn is inserted immediately after any one PC’s turn in the initiative order.

Paragon Fury. The creature may take one additional turn in each round of combat for each of its hit point pools that have been reduced to zero. The creature determines initiative normally for its first turn, though it gains advantage on the roll. Each subsequent turn the creature gains is inserted immediately after any one PC’s turn in the initiative order.

NOTE: Paragon Exhaustion and Paragon Fury are mutually exclusive. A Paragon Boss creature has one or the other, not both.

NOTE2: Notice later how with high CR monsters that I’ve transformed into BSSs that I do not give them Paragon Fury nor Paragon Exhaustion. These two features are for when you create your Paragon Boss Monster by stacking multiple low CR creatures into one higher CR Boss creature, e.g. stacking four CR 1/4 wolves on top of each other to create one CR 1 Boss Wolf. If you’re just splitting a high CR’s normal Hit Points into multiple pools, then these features are not warranted.

The 5 Types

a) Damage Mitigation, b) Condition Mitigation, c) Mobility, d) Forced Movement Capability, e) Out of Turn Effects.

Damage Mitigation:

To me at least, this is the least significant of all of the kinds of features available. It’s good for dragging fights out longer without necessarily making them any more interesting nor complex. Ideal use: Utilize for multi-stage encounters, e.g. when its 1st hitpoint pool from Paragon Fortitude reaches zero, a Quick BBS might unleash a cascade of giant rolling logs and use his Evasion to mitigate any damage dealt to himself; when it is reduced to its last hitpoint pool from Paragon Fortitude, a Rough high AC BBS might throw off its heavy armor and transform into a low AC, Resistance-laden beasty. Personally, a better form of damage mitigation is to get your BBS out of danger, e.g. Out of Turn Mobility abilities.

Condition Mitigation:

I assert the following: Legendary Resistance sucks donkeybrains. It’s incredibly metagamey for PCs when they are made aware that an enemy has legendary resistance. “Let’s burn three save spells/effects knowing that that’s a precondition to actually having a chance at affecting the beasty”. When you scroll down to the inserts, you will find a Condition Mitigation feature that I have ported from 4e called Bite the Bullet. I love it for reasons laid out in my Designing Big Bad Mechanics article. Note that AngryGM’s Paragon Hit Points already incorporates a form of condition mitigation, which is excellent. For BBSs that are truly alone, such a thing is almost essential.

Mobility:

This and Out of Turn Effects are probably the most important mechanics for BBSs. You have to keep your BBSs moving! Make your players earn every attack they make with every step they take. A player becoming unable to make an attack one turn against a creature due to the creature being out of reach should not be unheard of.

Forced Movement Capability:

The primary importance of this is to grant your BBS a means by which to protect itself from being surrounded and locked down. Most notably useful against Sentinel feat users. A secondary benefit is to put PCs in awkward positions that may imperil them and provoke creative solutions. It was not the Balrog’s blazing blade nor breath of fire that felled Gandalf but its pulling whip after all.

Out of Turn Effects:

07/08/2019: This section has been rewritten to reflect my most current understanding.

In 5e boss monster design, Legendary Actions are the primary source for Out of Turn Effects. One big concern I have with them is that they are “inevitable”, in the sense that they have no direct relationship with what the PCs are doing at any given moment. In response, I came up with a new mechanic, Legendary Reactions (seen below), that rely on PCs to trigger the Out of Turn Effects. Then, if the PCs can identify what the triggers are, they may be able to mitigate or prevent these Legendary Reactions from occurring, encouraging a more involved and dynamic encounter approach.

However, put in to practice I have found that Legendary Reactions should not replace Legendary Actions, but rather they should supplement one another depending on the circumstances. The primary value of Legendary Actions is in wanting to make a BBS stronger but feeling that Paragon Fury/Exhaustion would make the BBS too strong for your needs. Paragon Fury/Exhaustion is typically used when stacking multiple creatures on top of each other, and the encounter Challenge Rating is calculated as if the encounter had those stacked creatures individually counted in the encounter, but stacking an Adult Dragon on top of another Adult Dragon would create a max tier challenge when you really only want to make an encounter CR of about 2 or 3 points higher than one Adult Dragon.

So Legendary Actions are a good substitute for when Paragon Fury/Exhaustion would be too much. When you’re transforming a high CR monster into a BBS, then it’s probably a good idea not to use Paragon Fury/Exhaustion and instead use Legendary Actions. Either way, there should always be some Legendary Reactions to foster that dynamic encounter engagement.

New Big Boss Mechanics:

Legendary Reactions

What is a legendary reaction? A legendary reaction is a kind of reaction that has one use per turn rather than per round. A creature with a legendary reaction can make one reaction on each creature’s turn rather than once per round. When designing legendary reactions, it is important to define triggers for each. PCs should be encouraged to find ways to mitigate or prevent the activation of these triggers by gaining intel and observing the creature in battle.

Fortitude Recharges.

What is a Fortitude Recharge? A Fortitude Recharge is an ability that has one use between short rests, but can be regained by fulfilling some specified condition, typically when one hit point pool from Paragon Fortitude is reduced to 0. Sometimes, when an ability is recharged in this way, the ability can be used immediately as a reaction.

07/08/2019: All Fortitude Recharge language has been revised to be slimmer. Nothing of substance has changed.

The Inserts

These inserts will be organized beneath the three BBS categories: The Rough, The Quick, and the Sublime. Regarding damage, these features are not designed to deal an overwhelming amount of damage to PCs, but rather spread small amounts of damage to as many PCs as possible. Feel free to increase or decrease the damage dealt, as well as any DCs, as warranted by your BBS.

Fortitude Recharge abilities should, if they deal damage, deal on average a little more than the average of one Attack Action from the BBS, assuming it’s intended to damage as many PCs as possible.

If a Legendary Reaction deals damage, then it should deal maybe half or equal to the damage of a single attack from the BBS.

Rough BBSs often make fewer but stronger attacks, while Quick BBSs will often make more but weaker attacks, so damage-dealing Legendary Reactions from Rough BBSs should be a smaller fraction of one of its attacks while from Quick BBSs should be a larger fraction. You can see examples of this at the bottom of this essay. Each insert will include a CR value dictating by how much you should increase the CR of the creature for including the insert. This value is an approximation based on AoE and damage dice given – do not overly rely on it. If the encounter seems harder or easier in practice and not due to lopsided rolls on one side, adjust CR and the experience your PCs earn accordingly.

But before all of that, let’s look at Condition Mitigation. Directly ported from 4e, here is the quintessential Condition Mitigation feature essential to most any BBEG:

07/08/2019: Bite the Bullet updated to add additional condition end.

Bite the Bullet. As an Action, end one condition afflicting this creature and take 5 damage. This damage cannot be reduced in any way. If the condition prevents this creature from taking an Action on its turn, then it can use this ability to end that condition at the end of its turn.

Apply this to your primary BBEGs or those BBSs who don’t have any or many Paragon Hit Point Pools. If you do so, then remove Legendary Resistance if it has it. Probably remove Legendary Resistance even when it has many Paragon Hit Point Pools. Magic Resistance as well may not be warranted at all. If 5 damage does not seem enough, than increase it to 10, 15, or whatever is appropriate for the strength of your PCs and your monster. You may consider tying the damage to the spell slot level cast: Levels 1 to 2, 5 damage. 3 to 5, 10 damage. 6 to 7, 15 damage. 8 to 9, 20 damage. If there is no spell slot level, then the level of the PC inflicting the punishment may function: 1-4, 5 damage; 5 to 10, 10 damage; 11 to 15, 15 damage; 16 to 20, 20 damage.

07/08/2019: As a result of 1.5+ years of playtesting, the subsequent base DCs and damage values for the charges have been increased.

The Rough

Bigger = Badder. Low on technique, high on crushing you into the ground.

The Charge

The “charge” is the most basic and essential part of any beefy BBS. It accomplishes many critical needs at once: It keeps your BBS moving, it keeps your PCs moving, it can pressure multiple PCs at once, and it can help your BBS reach the back line. The stronger and more complicated your BBS, the more powerful and dynamic the charge will often be. Mobility, AoE damage, Forced Movement, and Out of Turn Effects can be combined into a single “charge” ability. The following inserts will depict in order increasingly more powerful and dynamic charges.

07/08/2019: The Strength saving throw effect against charges has been changed from ending the charge on a success to granting advantage to the next creature in the line on a success.

Stampeding Charge. Once per short rest, as an action, this creature moves up to its speed on the ground in a straight line. Creatures in the way of this line must make a DC11 Dexterity saving throw, taking 2d10 bludgeoning damage on a failed save, or half on a success. Either way, affected creatures are pushed outside of its path. Alternatively, a creature can make a DC13 Strength saving throw, taking half damage and granting advantage on the next saving throw against the charge on a success.

Fortitude Recharge: When one Hit Point pool is reduced to 0, stampeding charge recharges and can be used immediately as a reaction.

Increase CR by 1.

Flying Charge. Once per short rest, as an action, this creature moves up to its speed in any direction in a straight line. Creatures in the way of this line must make a DC13 Dexterity saving throw, taking 3d10 bludgeoning damage on a failed save, or half on a success. Either way, affected creatures are pushed outside of its path. Alternatively, a creature can make a DC15 Strength saving throw, taking half damage and granting advantage on the next saving throw against the charge on a success.

Fortitude Recharge: When one Hit Point pool is reduced to 0, flying charge recharges and can be used immediately as a reaction.

Increase CR by 1.

Ricocheting Charge. Once per short rest, as an action, this creature moves up to its speed on the ground in a line, changing direction any number of times during the charge. Creatures in the way of this line must make a DC13 Dexterity saving throw, taking 3d10 bludgeoning damage on a failed save, or half on a success. Creatures cannot suffer this damage more than once per charge. Either way, affected creatures are pushed outside of its path. Alternatively, a creature can make a DC15 Strength saving throw, taking half damage and granting advantage on the next saving throw against the charge on a success.

Fortitude Recharge: When one Hit Point pool is reduced to 0, ricocheting charge recharges and can be used immediately as a reaction.

Increase CR by 1.

Flying Ricocheting Charge. Once per short rest, as an action, this creature moves up to its speed in any direction in a line, changing direction any number of times during the charge. Creatures in the way of this line must make a DC15 Dexterity saving throw, taking 4d10 bludgeoning damage on a failed save, or half on a success. Creatures cannot suffer this damage more than once per charge. Either way, affected creatures are pushed outside of its path. Alternatively, a creature can make a DC17 Strength saving throw, taking half damage and granting advantage on the next saving throw against the charge on a success.

Fortitude Recharge: When one Hit Point pool is reduced to 0, flying ricocheting charge recharges and can be used immediately as a reaction.

Increase CR by 2.

Side note: I once gave one Dire Wolf in an encounter of 3 Dire Wolves and maybe 6 wolves a variant flying ricocheting charge. However, the damage was dramatically reduced and it didn’t use the flying ricochet to target multiple PCs but instead bounce from tree to tree surrounding the PCs, keeping it mobile, attempting to target the one PC it had developed a grudge against. It was a great intimidation tactic that made the players question the creature’s position and motives without actually dealing significant damage to the PCs.

If your BBS has multiple Hit Point Pools, you might consider granting it a Charge ability only after the 1st Hit Point pool has been eliminated, or granting it a stronger Charge ability at successive Hit Point pools.

Status Effects

07/08/2019: Area of Effect range has been slightly increased.

Rather than dealing damage directly, the following features attempt to deploy some kind of status effect to enemy creatures. Because we’re dealing with a Rough BBS, these effects will mostly be pushing and proning. Because these are status effects rather than damage, change in CR will be difficult to determine, so I won’t provide them. The change in CR though should either be negligible or at most an increase of 1.

Shake the Ground. Once per short rest as a bonus action this creature can cause creatures on the ground within 15 ft. of it to be pushed a number of ft. equal to its Strength modifier x 5 and make a DC12 Strength saving throw, falling prone on a failed save.

Fortitude Recharge: When one Hit Point pool is reduced to 0, shake the ground recharges.

Shake the Sky. Once per short rest as a bonus action this creature can force creatures within 30 ft. of it to be pushed a number of ft. equal to its Strength modifier x 5 and make a DC14 Strength saving throw, falling prone on a failed save.

Fortitude Recharge: When one Hit Point pool is reduced to 0, shake the sky recharges.

Frightening Roar. Once per short rest, as a bonus action, this creature can force creatures within 60 ft. of it to make a DC10 Wisdom saving throw, becoming frightened until the end of their next turn on a failed save.

Fortitude Recharge: When one Hit Point pool is reduced to 0, frightening roar recharges.

Damage Mitigation features

As opposed to defensive features that stay constant throughout an encounter, e.g. damage resistances and immunities, here are short term and Paragon Fortitude contingent damage mitigation features.

Invigorating Stamp/Shout. Once per short rest as a bonus action this creature can expend a number of hit dice up to its proficiency bonus and gain that much in Temporary Hit Points and force creatures within 30 ft. of it to succeed on a DC12 Strength saving throw or be pushed 10 ft. These temporary hit points last for one minute.

Feral Bulwark. When one Hit Point pool is reduced to 0, this creature gains resistance to all damage types except psychic. This lasts until the current Hit Point pool is reduced to 0.

Feral Rage. When one Hit Point pool is reduced to 0, this creature gains resistance to all damage types except psychic. This resistance lasts for 1 minute, or until it either fails to make an attack on its turn or does not take any damage for an entire round.

Mutating Bulwark. When one Hit Point pool is reduced to 0, this creature gains resistance to the damage type of the damage that reduced this creature’s Hit Point pool to 0. If this creature has multiple Hit Point pools, then decide whether these resistances will replace one another or be cumulative.

Also consider granting a Rough BBS the Barbarian’s Reckless Attack feature, perhaps when it is reduced to its last Paragon Fortitude hit point pool, i.e. “All attacks made by and against it are done with advantage”.

Legendary Reactions

These take the place of or supplement Legendary Actions, depending on your selection of Legendary Actions, Legendary Reactions, and per short rest abilities. Try to balance between damage dealing abilities and status effect dealing abilities. If you have Paragon Fury/Exhaustion and Legendary Reactions, then you likely don’t need Legendary Actions. These Legendary Reaction abilities incorporate Out of Turn Damage and Forced Movement. They typically use the conditional, “If an attack against this creature misses”, effectively punishing misses and rewarding hits. Rough BBSes often have low or middling AC, and this is designed with that in mind. With high AC Rough BBSes, a different conditional may be warranted, such as “When an enemy ends its turn and there are no enemies adjacent to the BBS” or “When the BBS succeeds a saving throw”.

Grab and Toss. Whenever a creature misses an attack against this creature, it can as a legendary reaction make a grapple attempt against a creature smaller than this creature within its melee reach if it has an open hand. If the grapple attempt succeeds, it can throw the grappled creature to a space within its Strength modifier x 10 ft. The thrown creature can make a DC10 Acrobatics check to land on their feet safely, taking 1d6 bludgeoning damage on a failed save.

If another creature is in that space, then that creature must make a DC12 Dexterity saving throw, both creatures taking 1d6 bludgeoning damage and falling prone on a failed save or dealing no damage and landing prone in an adjacent empty space on a success. Alternatively, the creature in that space can if they have a free hand make a DC12 Strength saving throw to catch the thrown creature, taking no damage and keeping the thrown creature upright on a success, and both creatures taking 1d6 damage and falling prone on a fail.

Intimidating Stamp/Shout. Whenever a creature within this creature’s melee reach misses an attack against it, it can as a legendary reaction force adjacent creatures to make a DC12 Strength saving throw, being pushed 5 feet on a failed save.

Bound. When an enemy ends its turn and there are no incapacitated enemies adjacent to this creature, this creature can as a legendary reaction leap to an empty space within half its base movement speed.

Harry. Whenever a creature within half of this creature’s base movement speed ends its turn with no other creatures adjacent to it, this creature can as a legendary reaction leap to the nearest space adjacent to that creature.

Loogie Shot. Whenever this creature succeeds on a saving throw, it can spit sticky saliva at a creature within 60 ft. of it. The target creature makes a DC11 Dexterity saving throw, reducing its speed to 0 on a failed save so long as the saliva remains. A creature can as an action break itself or an adjacent creature free from the saliva with a DC14 Strength check. A glob of saliva has 5 AC, 5 hit points, is immune to bludgeoning, piercing, and slashing damage, and is resistant or immune to any damage type this creature is resistant or immune to.

The Quick

Generally, Quick BBSs kill by a thousand cuts as opposed to the Rough BBSs slower, heavier crashes, so QuickBBSs don’t really need heavy damaging abilities like a charge. It is much more important for a Quick BBS to keep moving than it is for a Rough BBS, so let’s start with Legendary Reaction abilities first.

Legendary Reactions

The following options provide increasingly powerful Out of Turn Mobility. The first option, Side Step is for when you don’t want your Quick BBS to deal additional damage per round in this way.

Side Step. When an attack misses against this creature, it can as a legendary reaction move up to half its speed without triggering opportunity attacks.

CR+0

Side Step Riposte. When an attack misses against this creature, it can as a legendary reaction move up to half its speed without triggering opportunity attacks and make a single weapon attack during this movement.

CR+1

Teleporting Riposte. When an attack misses against this creature, it can as a legendary reaction teleport up to half its speed and then make a single weapon attack.

CR+1

Deflect. When a ranged weapon attack misses against this creature by 5 or more, it can as a legendary reaction deflect the attack back at the attacker. This creature makes a ranged weapon attack adding their proficiency bonus to the attack roll against the attacker, dealing the weapon’s damage as normal on a hit.

CR+0

Redirect. When a melee weapon attack misses against this creature by 5 or more, it can as a legendary reaction force the attacking creature to move a number of feet equal to this creature’s Dexterity modifier x 5 in any direction to an open space. If the attacking creature ends this movement with another creature within their melee weapon’s range, this creature can force the attacking creature to make a weapon attack with disadvantage against that creature.

CR+0

Somervault. If an attack made against this creature misses, and there is another creature adjacent to it, this creature can as a legendary reaction move to another empty space adjacent to that creature.

CR+0

Leg Sweep. If an adjacent creature’s attack misses against this creature, it can as a legendary reaction force that creature to make a DC10 Dexterity saving throw, falling prone on a failed save.

CR+0

Damage Mitigation

Because Quick BBSs often have less health than a comparable BBS, damage mitigation is a little more important. Fortunately, the PHB provides excellent and simple damage mitigation features in Evasion and Uncanny Dodge. The more powerful the Quick BBS, the more likely it is to have one or both of these features.

Evasion. When you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail.

CR+1/2

Uncanny Dodge. When an attacker you can see hits you with an attack, you can use your reaction to halve the attack’s damage to you.

CR+1/2

Fortitude Recharges

For a Quick BBS, it is generally more important for Fortitude Recharge abilities to get them out of sticky situations than to deal damage. Being highly mobile and attacking frequently already allows them to spread damage around.

Reorient the Axis. Once per short rest, as an action, this creature can forcibly move creatures within 15 ft. of it to an empty space on the ground within range. Affected creatures must succeed on a DC12 Constitution saving throw or fall prone.

Fortitude Recharge. When one Hit Point pool is reduced to 0, reorient the axis recharges and can be used immediately as a reaction.

Leap. Once per short rest, when this creature takes damage, this creature can as a reaction move up to its speed in a straight line without triggering opportunity attacks.

Fortitude Recharge. When one Hit Point pool is reduced to 0, leap recharges and can be used immediately as a reaction.

Greater Leap. Once per short rest, when this creature takes damage, this creature can as a reaction move up to twice its speed in a straight line without triggering opportunity attacks. 

Fortitude Recharge. When one Hit Point pool is reduced to 0, greater leap recharges and can be used immediately as a reaction.

Flying Leap. Once per short rest, when this creature takes damage, this creature can as a reaction fly up to its speed in a straight line without triggering opportunity attacks. It must end this movement on a surface or begin to fall.

Fortitude Recharge. When one Hit Point pool is reduced to 0, flying leap recharges and can be used immediately as a reaction.

Greater Flying Leap. Once per short rest, when this creature takes damage, this creature can as a reaction fly up to twice its speed in a straight line without triggering opportunity attacks. It must end this movement on a surface or begin to fall.

Fortitude Recharge. When one Hit Point pool is reduced to 0, greater flying leap recharges and can be used immediately as a reaction.

With all of these fantastic mobility features, it may not be warranted to also grant your Quick BBS access to any variant of the Rogue’s Cunning Action, though that remains to be seen when put into practice.

The Sublime

OK. Umm, spellcastery BBSs don’t really need special abilities beyond Bite the Bullet, because they get most of what they need from spells. AoE damage, status effects, damage mitigation, mobility, forced movement and out of turn effects all easily come from spells like Fireball, Darkness, Shield, Absorb Elements, Dimension Door, Blink and so on.

However, that certainly does not mean any spellcaster pulled from the Monster Manual can be a BBS; far from it! In fact, it’s probably more likely for Sublime types to either destroy the PCs immediately, or be destroyed immediately. Fact of the matter is, Sublime BBSs should actually not be solos.

Which isn’t to suggest that you shouldn’t make Sublime solos, but rather any Sublime solo will almost inevitably become a hybrid with Rough and/or Quick. A Lich BBS could be a Sublime/Rough, with great damage mitigation due to its undying nature. A Githyanki BBS would make an excellent Sublime/Quick. A Vampire Lord, e.g. Strahd von Zarovich, could be a Sublime/Quick at first, fighting somewhat like a bladesinger might, and then become a Sublime/Rough when reduced to his last Paragon Fortitude hp pool. Many spellcasting monsters either immediately win or lose fights if they are alone depending on who gets the jump on whom, so to make combat results less extreme they’re going to end up either acquiring a lot of henchfolks or dabbling in Quick and/or Roughness.

That being said, let’s create some inserts for Sublime BBSes to supplement whatever spells they might cast. Our goal here is to increase the number of rounds a Sublime BBS survives, which means avoidance, mitigation and escape.

07/08/2019: I’ve decided to change some of the following triggers to when an attack against it hits instead of misses, because I think that Sublime BBSes typically have low hit points and don’t have good defenses. So whereas Roughs and Quicks exploit vulnerabilities and PC failures, Sublimes punish success, if only out of a sense of self preservation. Try it out and tell me what you think.

Defensive Push. If an adjacent creature’s attack against this creature hits, it can as a legendary reaction force the attacking creature to make a DC12 Strength saving throw, being pushed a number of ft. equal to 5 times its spellcasting modifier on a failed save.

CR+0

Greater Defensive Push. If an adjacent creature’s attack against this creature hits, it can as a legendary reaction force the attacking creature to make a DC14 Strength saving throw, being pushed a number of ft. equal to 10 times its spellcasting modifier on a failed save.

CR+0

Offensive Pull. If a ranged attack from a creature against this creature hits, it can as a legendary reaction force the attacking creature to make a DC12 Strength saving throw, being pulled a number of ft. equal to 5 times its spellcasting modifier on a failed save.

CR+0

Greater Offensive Pull. If a ranged attack from a creature against this creature hits, it can as a legendary reaction force the attacking creature to make a DC14 Strength saving throw, being pulled a number of ft. equal to 10 times its spellcasting modifier on a failed save.

CR+0

Warp Entrance. If another creature for the first time on their turn enters a space adjacent to this creature, it can as a legendary reaction force that creature to make a DC12 Dexterity saving throw, falling prone on a failed save.

CR+0

Warp Exit. If a creature for the first time on their turn moves out of reach from this creature, it can as a legendary reaction force that creature to make a DC12 Dexterity saving throw, falling prone on a failed save.

CR+0

Return Missile. If a ranged weapon attack against this creature misses by 5 or more, it can as a legendary reaction return the launched missile against the attacker. Make a spell attack roll and deal the weapon’s damage die plus this creature’s spellcasting modifier on a hit.

CR+0

Suscept Mind. If this creature succeeds on a saving throw forced by another creature, it can as a legendary reaction force that creature to make a DC10 Intelligence saving throw, suffering disadvantage on the next saving throw they make until the end of this creature’s next turn on a failed save.

CR+0

If we’ve got a Teleportation themed BBS, then consider the following:

Teleporting Step. If an attack against this creature hits, it can as a legendary reaction teleport to an empty space within a number of feet equal to half its speed.

CR+0

Greater Teleporting Step. If an attack against this creature hits, it can as a legendary reaction teleport to an empty space within a number of feet equal to its speed.

CR+0

Meditation upon Time and Space. Once per short rest, this creature can as a bonus action force creatures within a 15 ft. radius to make a DC13 Intelligence saving throw, being teleported to another space within 15 ft. on a failed save. 

Fortitude Recharge: When one hit point pool is reduced to 0, meditation upon time and space recharges and can be used immediately as a reaction.

CR+0

Mass Random Teleport. Once per short rest, this creature can as a bonus action force creatures within a 30 ft. radius to make a DC15 Intelligence saving throw. On a failed save, a target rolls a 1d12, being teleported a number of feet equal to 5 times the result in a random direction.

Fortitude Recharge: If this creature has Paragon Fortitude, then when one hit point pool is reduced to 0, mass random teleport recharges and can be used immediately as a reaction. 

CR+0

Status Effects.

Lightning Skin. If a creature hits this creature with a melee weapon attack, this creature can as a legendary reaction force that creature to make a DC12 Dexterity saving throw, losing its reaction until the end of this creature’s next turn on a failed save.

CR+0

Anchor the Body. Once per short rest, when one of your Paragon Fortitude hit point pools reach zero, this creature can as a reaction summon spectral hands from its body. Each creature within 30 ft. must make a DC12 Dexterity saving throw, becoming grappled on a failed save. A grappled creature can as an action make a DC14 Athletics or Acrobatics check to escape. This creature must maintain concentration as if it were concentrating on a spell to maintain this feature.

CR+0

Anchor the Mind. Once per short rest, when one of your Paragon Fortitude hit point pools reach zero, this creature can as a reaction summon spectral hands from its body. Each creature within 30 ft. must make a DC14 Intelligence saving throw, becoming restrained on a failed save. A restrained creature can repeat their saving throw at the end of each of its turns to escape. This creature must maintain concentration as if it were concentrating on a spell to maintain this feature.

CR+1

Anchor the Soul. Once per short rest, when one of your Paragon Fortitude hit point pools reach zero, this creature can as a reaction summon spectral hands from its body. Each creature within 30 ft. must make a DC16 Wisdom saving throw, becoming paralyzed on a failed save. A paralyzed creature can repeat their saving throw at the end of each of its turns to escape. This creature must maintain concentration as if it were concentrating on a spell to maintain this feature.

CR+2

Beyond this, have your standard spells like Absorb Elements, Hellish Rebuke, Dimension Door, Shield, etc.

I’ve got one more for ya, a defensive mobility ability.

Skeletal Guardian Wings. Once per short rest, as a bonus action, this creature can summon a pair of skeletal wings. Each wing has 2 to 6 spines. Whenever an attack would hit this creature, this creature can cause one spine to shatter instead, negating the attack. A critical hit against this creature requires two spines to negate. So long as this creature has at least 1 spine on each wing remaining, it has a 20 ft. fly speed.

I made this on the spot when I decided that a plain corpse my PCs had come across in the Curse of Strahd would be a monsterific undead horror instead. I gave him hit points, AC, and abilities on the fly, like being able to cast the Darkness spell, Inflict Wounds, and the aforementioned wings. Didn’t build him like a BBS, however. Just wanted to make him as visually and vocally scary as hell, as well as survive more than 2 rounds, hence the wing ability. One of his wings had 4 spines, the other had 3.

Examples

Here are some BBSs I’ve designed. In order, we have

Some abilities only activate when a certain Paragon Fortitude hit point pool is reached. These abilities will have the phrase, “1st pool”, “2nd pool”, “3rd pool”, etc. to indicate when that ability becomes available.