Quackthulhu
Gargantuan aberration, chaotic evil
Armor Class
18 (natural armor)
Hit Points
429 (26d20 + 156)
Speed
50 ft., swim 100 ft.
STR
24 (+7)
DEX
14 (+2)
CON
22 (+6)
INT
5 (-3)
WIS
15 (+2)
CHA
20 (+5)
Damage Immunities
necrotic, poison
Damage Resistances
bludgeoning, piercing, and slashing from nonmagical attacks
Senses
blindsight 120 ft., darkvision 120 ft., passive Perception 15
Saving Throws
Str +12, Con +11, Wis +7
Skills
Intimidation +9, Perception +5
Languages
--
Challenge
21 (33,000 XP)
Legendary Resistance (3/day). If Quackthulhu fails a saving throw, it can choose to succeed instead.
Actions
Multiattack. Quackthulhu makes 4 attacks, one of which can be an Infect attack.
Tentacle. Melee Weapon Attack, +11 to hit, reach 15 ft., one target. Hit: 20 (3d8 + 7) bludgeoning damage, and the target must succeed on a DC 15 Strength saving throw or become grappled. Quackthulhu has four tentacles.
Infect. Melee Weapon Attack, +11 to hit, reach 5 ft., one target who is grappled. Hit: 17 (3d6 + 7) piercing damage, and the target must succeed on a DC 15 Constitution saving throw or become poisoned for one hour. While poisoned in this way, the target is considered infected.
Soul-wrenching Quack (Recharge 6). All creatures within 60 ft. of Quackthulhu must succeed on a DC 16 Wisdom saving throw or become paralyzed until the end of Quackthulhu’s next turn.
Legendary Actions
Quackthulhu can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. Quackthulhu regains spent legendary actions at the start of its turn.
Tentacle. Quackthulhu makes a tentacle attack.
Ground Slam. All creatures within 5 ft. of Quackthulhu must succeed on a DC 14 Strength saving throw or be pushed 10 ft. away.
Command Infected. A creature within 60 ft. of Quackthulhu who is currently infected moves up to half its speed and makes a single weapon attack against a creature of Quackthulhu’s choice.