BBEG Encounters that don't use Legendary/Lair Stuff

[NewDM]

I'm wanting to get a list of BBEG encounters (of any level) that would challenge a party and last at least 5 rounds without using Legendary Actions, Legendary Saves, or Lair Actions. This can be used as a community reference and for ideas for those that dislike Legendary and Lair stuff.

Things to be aware of:

Try to prevent total lock down of the BBEG through Paralyze, Stun, or other action denial effects.
Don't completely obviate the abilities of players (a few immunities to damage or conditions is fine) such as complete magic or weapon immunity unless its a creature that already has that.


I'll go first:

Environment
The room is a 80 foot by 60 foot open cavern with stalagmites and stalactites the ceiling is 40 feet up and there are 6 large pillars where stalagmites and stalactites meet. Each of them have 10 hp, AC 12, Immune to Poison Psychic damage and conditions and are Resistant to everything except for force damage.

Party Level
This encounter is for a party of 4 level 6 characters.

Monsters
Korimi Koichi(Ninja Assassin)
Drow Humanoid, Chaotic Evil
AC 17 (Studded Leather, Dex)
HP 130 (21d8+24)
Speed 40 feet Climb 30 feet
STR 14(+2) DEX 20(+5) CON 14(+2) INT 12(+1) WIS 12(+1) CHA 12(+1)
Skills Initiative +10, Stealth +11, Perception +7, Acrobatics +11, Deception +7
Condition Immunities sleep
Senses Dark Vision 60 ft. Passive Perception 14
Languages common, elvish
Challenge 6 (2,300xp)
Traits

Fey Ancestry. Advantage on Charm saving throws.

Alert. The Ninja Assassin cannot be surprised and has +5 on Initiative checks (calculated into stat block).

Lucky Can roll an extra dice and then choose which dice to use on attack rolls, saving throws, and ability checks. Can also use it to force an attacker to roll an extra dice and then choose which dice to use for the attack. Can do this 3 times per long rest.

Assassinate Points
The Ninja Assassin has 3 Assassinate Points. When the Ninja Assassin makes a successful attack with advantage or while hidden from the target instead of dealing Sneak Attack damage, they can expend an Assassinate Point and choose to do any of the following:
Force the target to make a DC 15 Constitution saving throw or become Paralyzed, the target can repeat the saving throw at the start of each of their turns to become free of the effect.
Force the target to make a DC 15 Dexterity saving throw or take 1d6 poison damage each round, repeating the save at the start of their turn to end the effect.
Force the target to make a DC 15 Strength saving throw or have their movement reduced to 0, repeating the saving throw at the start of each round to remove the effect.
One Assassinate Point is recovered each time the Ninja Assassin scores a critical hit, or deals sneak attack damage up to a maximum of 3.

Sneak Attack
Once per turn when the Ninja Assassin deals damage to an enemy they can add 3d6 damage to the attack. This damage is doubled on a critical hit.

Actions
Multi-Attack. The Ninja Assassin makes two Dagger attacks or two Sweeping Slash attacks, and then uses Smoke Cloud.

Dagger. Melee Weapon Attack: +6 to hit, reach 5 ft., one target.
Hit: 1d4+5 (see Sneak Attack and Assassin Points above). The target must make a DC 15 Constitution saving throw or become Poisoned.

Sweeping Slash. The Ninja Assassin makes a Dagger attack at all enemies within 5 feet with disadvantage. After this the Ninja Assassin can move away without provoking opportunity attacks.

Smoke Cloud The Ninja can use a bonus action to throw a smoke pellet at the ground. This fills a 15 foot radius sphere centered on the Ninja Assassin with Heavy Obscurement. The ninja can then Hide as part of this action. The Ninja has 10 smoke pellets. These pellets requires special knowledge and Ki focus to use and are unusable by someone that did not craft them.

Reactions
Shadow Copy. As a reaction when the Ninja Assassin is hit and would take damage or gain a condition, they can expend an Assassin Point and a Shadow Copy (see below) is created. It takes the damage or gains the condition instead of the Ninja Assassin from the triggering attack. The Ninja Assassin can have no more than 3 shadow copies active at a time. Each Shadow Copy rolls initiative, acts on its turn, and looks and acts exactly like the Ninja Assassin. A DC 8 Perception check (as an action) can be used to determine whether this is the real Ninja Assassin.

Instinctual Smoke Cloud. As a reaction when targeted by a ranged attack the Ninja Assassin can expend an Assassin Point to use a smoke pellet as per Smoke Cloud above.

Uncanny Dodge. When an attacker that the Ninja Assassin can see hits them with an attack, they can use their reaction to halve the attack's damage.

Shadow Copy
Drow Humanoid, Chaotic Evil
AC 15 (Dex)
HP 30 (5d8+6)
Speed 20 feet Climb 10 feet
STR 14(+2) DEX 20(+5) CON 14(+2) INT 12(+1) WIS 12(+1) CHA 12(+1)
Skills Initiative +10, Stealth +11, Perception +7, Acrobatics +11, Deception +7
Condition Immunities sleep
Senses Dark Vision 60 ft. Passive Perception 14
Languages common, elvish
Traits

Fey Ancestry. Advantage on Charm saving throws.

Sneak Attack
Once per turn when the Ninja Assassin deals damage to an enemy they can add 3d6 damage to the attack. This damage is doubled on a critical hit.

Actions
Dagger. Melee Weapon Attack: +6 to hit, reach 5 ft., one target.
Hit: 1d4+5 (see Sneak Attack above). The target must make a DC 15 Constitution saving throw or become Poisoned.

Reactions
Uncanny Dodge. When an attacker that the Ninja Assassin can see hits them with an attack, they can use their reaction to halve the attack's damage.

Strategy
The Ninja Assassin will Hide using the Stalagmites and Stalactites as cover. They will then sneak out and attack enemies trying to disable as many as possible. When possible they will use Shadow Copy until 3 copies are created and then continue to strike from behind cover.

[RickAllison]

One thing I like to add to bosses is the so-called Combo Breaker. When sufficient damage is dealt within a round or enough time is passed immobilized, the boss has a reaction that renders him invincible until his regular turn and gives him a free turn that functions like a regular one. It keeps things simple while preventing lock-outs.

Also, abilities that trigger with HP loss. Final Fantasy's Limit Breaks are kind of what I think here. I used a boss recently who would go into dark modes when he was at 2/3 and 1/3 health. Went from giving out two regular attacks, to adding in a line-based blast with one of the attacks, to occasionally bursting into a round of invincibility where he would make six attacks on the first turn and then six more and an AoE at the end of the second. He couldn't do it much, but it gave a devastating nova when the party thought he was beat.

[Malifice]

An appropriate 'hard' Solo Boss monster for 4 x 6th level PCs is a CR 9 critter.

A bone devil, nycaloth or young blue dragon would pose an adequate threat for mine.

[TheTeaMustFlow]

Devils and Demons, particularly the Pit Fiend, are good for this, as is the Death Knight.

[NewDM]

This is not for discussing them. This is for posting actual encounters.

[DragonBaneDM]

This is not for discussing them. This is for posting actual encounters.

To be totally fair, the title makes it sound like you're at least partially interested in monsters that could serve as bosses without having their own Legendary or Lair actions. Most players and even a fair amount of DMs don't have a homebrewed boss lying around.

But I'm not most of 'em, so here's mine:

Mockvast Clique:
Terrain of Note: Doesn't fit your bill terrain wise, but is easily modified, this fight was originally in the Feywild in a huge faerie ring, and given swarm rules can easily challenge any party of 4th Level.

Mushrooms: There are 6 giant mushrooms in this battle. Four are Large with Medium trunks and two are Huge with Large trunks. They provide several advantages:
• They can provide three-quarters cover: +5 to AC and Reflex saving throws.
• Large mushrooms can be felled with two actions used to attack and weaken the trunks and the Huge with three. A fallen mushroom acts as half cover: +2 to AC and Reflex saving throws.
• Climbing a mushroom and jumping off as part of a melee attack allows a character to make an attack that ignores the Swarm ability of the Mockvast Clique as their melee attack will pass through multiple fairies on the way down and deal full damage.
• Making a ranged attack from the top of a mushroom puts the character on eye level with the fairies and provides advantage to their attack roll.
• The Huge mushrooms take a longer time to climb up, a full action instead of half movement, BUT they’re out of range from the Clique’s “Gnashing Swarm” and “Swarm Form” abilities.

Spores: At the beginning of each round, two spores spawn at random adjacent to two random mushrooms. There are three types of spores. Each has an AC of 13 to attack, disappears when they are successfully attacked, and move 2 squares in a random direction each turn. They float 10 feet above the ground and can be identified with a DC 15 Nature check. There can be a maximum of 6 spores on the battlefield at once.
Green Spore: Creatures adjacent to a green spore when it is attacked regain 2d10 hit points.
Violet Spore: Creatures adjacent to a violet spore when it is attacked take 2d10 poison damage.
Blue Spore: Creatures adjacent to a blue spore when it is attacked gain advantage on their next attack roll.
(None of these have been revealed yet)

Corpse Piles: Any time the Clique takes 20 or more damage in a single turn or turns from one form to another, it produces a ring of dead fairies in the squares adjacent to it. This is difficult terrain.

Throughout the fight the PCs can attempt DC 15 skill checks as a bonus action:

Athletics: A player is able to climb Large mushrooms with a bonus action instead of a move action and a Huge mushroom by using a bonus action and half of their movement instead of an action.
Arcana: As a bonus action, the player can destroy a Mockvast Fairie within range of their attack.
Nature: The character identifies a spore within range.
Survival: As a bonus action, the player can destroy a spore within range of their attack.
Acrobatics: On success the character ignores difficult terrain until the end of their turn.

Mockvast Clique is going to be 1350 XP. It's a paragon monster, the idea being you take 2 monsters and put them inside each other. "Kill" one and it loses half its actions

Stage 1 Stats (Caster): 60 HP AC: 15 Damage: 22 Attack: N/A Save 15
Stage 2 Stats (Giant): 70 HP. AC: 13 Damage 25. Attack +7. Save: 13

The MockVast Clique, The Swarm Awakens Stage 1
Huge fey
AC: 14
HP: 60
Speed: 8
Initiative: +2
Ability Scores: Str 20 (+5) Con 19 (+4) Dex 15 (+2) Int 5 (-3) Wis 10 (0) Cha 6 (-3)
Proficient Saving Throws: Con Cha
Senses: Perception +0 Low light vision
Languages: Sylvan
CR: 2
TRAITS:
Instinctive Spawning: At 10 + MockVast Clique’s initiative, two Mockvast Faeries spawn adjacent to the Clique and take their turn immediately.
Swarm: The Mockvast Clique has resistance against attacks and spells that target one creature, but has vulnerability to spells and abilities that target more than one square.
ACTIONS:
Fist of Fairies: Area burst 2 within 3. Does not provoke OAs. +7 vs AC: 2d8 + 1 piercing damage.
Gnashing Swarm: Close burst 3: DC 13 Constitution save: Targets take 3d8 damage and is pushed one square.
BONUS ACTIONS:
Mass Faerie Fire: Area burst 4 within 30. Provokes OAs. DC 15 Dexterity save or the target takes 2d6 fire damage and cannot become invisible, loses invisibility, and attacks against the targets have advantage while the Clique retains concentration. (DC 10 Con check or half damage taken)
Scintillating Spray: Close burst 3: DC 15 Wisdom save or the target takes 1d8+2 radiant damage and the target is blind until the end of their next turn.
Charm of the Defender: One creature. Ranged 10. Provokes OAs. DC 15 Charisma save or the target moves up to 3 squares (Clique does NOT get OAs neither do fairies) and makes a melee basic attack against one target of the Clique’s choice.

MockVast Fairy:
Tiny fey
AC: 14
HP: 1
Ability Scores: Str 4 (-3) Con 6 (-2) Dex 15 (+2) Int 5 (-3) Wis 10 (0) Cha 6 (-3)
ACTIONS:
Bite: +4 vs AC: 2 damage.

The Mockvast Clique, Swarming Storm Stage 2
Large fey
AC: 13
HP: 70
Speed: 8
Initiative: +2
Ability Scores: Str 20 (+5) Con 19 (+4) Dex 15 (+2) Int 5 (-3) Wis 10 (0) Cha 6 (-3)
Proficient Saving Throws: Con Dex
Senses: Perception +0 Low light vision
Languages: Sylvan
CR: 2
TRAITS:
Instinctive Spawning: At 10 + MockVast Clique’s initiative, one Mockvast Faerie spawns adjacent to the Clique and takes its turn immediately.
Swarm: The Mockvast Clique has resistance against attacks and spells that target one creature, but has
vulnerability to spells that target more than one square.
ACTIONS:
Stinging Breath: (Not useable in Gnashing Swarm form) Close blast 3 DC 13 Constitution save or 2d8 + 1 damage.
Swarm Form: Close burst 5. The Mockvast Clique disappears. The zone within the burst becomes difficult terrain and each enemy that starts its turn within the zone takes 5 damage. The PCs may target any square within the zone to attack the Clique, it has the same defenses and saving throws. This effect lasts until the Clique takes 20 damage, after which it reforms in its giant form.
Swarm’s Savagery: (Only useable in Gnashing Swarm form): Targets one creature within the zone. +7 vs AC: 1d6 + 4 damage and the target is grappled until it makes a DC 13 Strength check.

[eastmabl]

This is not for discussing them. This is for posting actual encounters.

I would recommend that you change the name of the thread, if possible.

[mephnick]

I like the assassin, but you're basically replacing legendary actions with a multi-attack smoke cloud, riders on a custom points system and reactions. Not a bad thing, but if you feel legenday actions are too "gamey" (the most common complaint) I'm not sure this is much different.

[NewDM]

I like the assassin, but you're basically replacing legendary actions with a multi-attack smoke cloud, riders on a custom points system and reactions. Not a bad thing, but if you feel legenday actions are too "gamey" (the most common complaint) I'm not sure this is much different.

Everything in the Ninja Assassin is a replicate or comparable to player actions. The reason I and many like me dislike Legendary stuff is because it comes off as a cheap fix that players cannot achieve, so this thread is a place to post builds that don't use Legendary/Lair stuff. If you want to discuss the merits Legendary/Lair stuff and their replacements, then please start a thread dedicated to that.

[JNAProductions]

Except it's not replicable by players. There is, as of yet, no way to exchange sneak attack damage for status effects.