Alkilith (5.5)

Medium Fiend (Demon), Typically Chaotic Evil
Armor Class 17 (natural armor)
Hit Points 168 (16d8 + 96)
Speed 40 ft., climb 40 ft.
STR
12 (+1)
DEX
19 (+4)
CON
22 (+6)
INT
6 (-2)
WIS
11 (+0)
CHA
7 (-2)
Saving Throws Dex +8, Con +10
Skills Stealth +8
Damage Resistances acid, cold, fire, lightning; bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities poison
Condition Immunities charmed, frightened, poisoned
Senses darkvision 120 ft., passive Perception 10
Languages understands Abyssal but can't speak
Challenge 11 (7200 XP)     Proficiency Bonus +4
Abyssal Rift.
Amorphous.
False Appearance.
Foment Confusion.
Magic Resistance.
Spider Climb.
Unusual Nature.
ACTIONS
Multiattack.
Tentacle.

This full creature's stat block is not available (not OGL).

Monsters of the Multiverse
Alkilith (5.5)