Armor Class 14 (natural armor)
Hit Points 285 (30d8 + 150)
Speed 20 ft., fly 30 ft.
Saving Throws STR +11, CHA +11
Skills Deception +11, Insight +10, Intimidation +11, Persuasion +11
Damage Resistances acid, cold, [object Object]
Damage Immunities fire, poison
Condition Immunities charmed, poisoned
Senses darkvision 120 ft., passive Perception 14
Languages all, telepathy 120 ft.
Challenge 18
Stench of the Slug. Any creature that starts its turn within 10 feet of the avatar must succeed on a DC 19 Constitution saving throw or have the poisoned condition until the start of their next turn. On a successful saving throw, the creature is immune to this stench for 1 hour.
Multiattack. The avatar makes four Sickening Claw attacks. It can replace one of the attacks with Insect Gorge (if available).
Sickening Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) slashing damage plus 13 (3d8) acid damage. The target's hit point maximum is reduced by the acid damage taken. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.
Insect Gorge (Recharge 4–6). The avatar disgorges a swarm of biting flies at a point it can see within 300 feet of itself. Each creature within a 20-foot-radius sphere centered on that point must make a DC 19 Constitution saving throw. A creature takes 55 (10d10) piercing damage on a failed save, or half as much damage on a successful one. The biting flies persist for 1 minute or until the avatar is slain. A creature must also make this saving throw when it enters the insects' area for the first time on a turn or ends its turn there.
Caustic Slimepool (1/Day). The avatar causes caustic slime to emanate from itself, covering a 15-foot-radius circle. Each creature within the slime must succeed on a DC 19 Dexterity saving throw or have the grappled condition (escape DC 17). A grappled creature takes 21 (6d6) acid damage at the start of its turn.
CoA, p. 38