Greater Death Butterfly Swarm

Huge Beast (Swarm), chaotic evil

Armor Class 15 (natural armor)

Hit Points 84 (13d12)

Speed fly +40, walk +5, hover true

Challenge 6

STR
1
-5
DEX
16
+3
CON
10
+0
INT
1
-5
WIS
15
+2
CHA
12
+1

Damage Vulnerabilities cold, fire

Damage Resistances bludgeoning, piercing, and slashing

Condition Immunities charmed, frightened, paralyzed, petrified, prone, restrained, petrified

Senses darkvision 60 ft., passive Perception 12

Special Abilities

Potent Poison. The death butterfly swarm's poison affects corporeal undead who are otherwise immune to poison.

Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny insect. The swarm can't regain hit points or gain temporary hit points.

Weight of Wings. As death butterfly swarm but with DC 16 Dexterity saving throw

Actions

Multiattack. The swarm makes a Bite attack against every target in its spaces.

Bites. Melee Weapon Attack: +6 to hit, reach 0 ft., every target in the swarm's space. Hit: 24 (6d6 + 3) piercing damage, or 13 (3d6 + 3) piercing damage if the swarm has half of its hit points or fewer. The target also takes 17 (5d6) poison damage and becomes poisoned for 1d4 rounds; a successful DC 15 Constitution saving throw reduces poison damage by half and prevents the poisoned condition.

Source: Tome of Beasts · OGL/Open