Choromos Swarm

Huge swarm of Medium fiends, neutral evil

Armor Class 18 (natural armor)
Hit Points 299 (26d12 + 130)
Speed 20 ft., fly 50 ft. (hover)

STR	DEX	CON	INT	WIS	CHA
14 (+2)	23 (+6)	20 (+5)	16 (+3)	19 (+4)	21 (+5)

Saving Throws Dexterity +13, Constitution +12, Intelligence +10, Wisdom +11
Skills Perception +11, Performance +12
Damage Resistances bludgeoning, piercing, slashing
Damage Immunities poison
Condition Immunities charmed, frightened, paralyzed, petrified, poisoned, prone, restrained, stunned
Senses blindsight 60 ft. (blind beyond this radius), passive Perception 21
Languages Abyssal, Common, Infernal
Challenge 22 (41,000 XP)

Special Traits

• Deranged Hum. At the start of each of the choromos’ turns, each creature within 5 feet of it takes 10 (3d6) psychic damage. Fiends are immune to a choromos’ Deranged Hum.
• Magic Resistance. The choromos has advantage on saving throws against spells and other magical effects.
• Magic Weapons. The choromos’ weapon attacks are magical.
• Swarm. The choromos can occupy another creature’s space and vice versa, and the choromos can move through any opening large for a Medium fiend. The choromos can’t regain hit points or gain temporary hit points.

Actions

• Multiattack. The choromos makes three Poisoned Claw attacks or two Screech attacks.
• Poisoned Claws. Melee Weapon Attack: +13 to hit, reach 0 ft., one creature in the swarm’s space. Hit: 35 (10d6) slashing damage, or 17 (5d6) slashing damage if the swarm has half of its hit points or fewer. The target must make a DC 20 Constitution saving throw, taking 18 (4d8) poison damage on a failed save, or half as much damage on a successful one.
• Screech. Ranged Spell Attack: +12 to hit, ranged 120 ft., one target. Hit: 45 (10d8) thunder damage and the target must succeed on a DC 20 Constitution saving throw or be incapacitated until the end of its next turn.
• Maddening Cacophony (recharge 5-6). The choromos’ many voices rumble into a maddening semblance of harmony. Each creature within 30 feet of the choromos that can hear it must make a DC 19 Wisdom saving throw. On a failure, a creature takes 70 (20d6) psychic damage and suffers one short-term madness. On a success, a creature takes half the damage and doesn’t suffer a short-term madness.