Magic Resistance. The ceremorph has advantage on saving throws against spells and other magical effects.
Multiattack. The ceremorph makes one Slam attack and one Tentacles attack. The ceremorph can replace one of the attacks with a Mind Bolt attack, if available.
Slam. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit:22 (4d8 + 4) bludgeoning damage.
Tentacles. Melee Weapon Attack: +7 to hit, reach 10 ft., one creature. Hit:15 (2d10 + 4) psychic damage. If the target is Large or smaller, it has the grappled condition (escape DC 14) and must succeed on a DC 15 Intelligence saving throw or have the stunned condition until this grapple ends.
Extract Brain. Melee Weapon Attack: +7 to hit, reach 5 ft., one incapacitated Humanoid grappled by the ceremorph. Hit:55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the ceremorph kills the target by extracting and devouring its brain.
Mind Bolt (3/Day). Ranged Spell Attack: +7 to hit, range 120 ft., one creature. Hit:17 (2d12 + 4) psychic damage, and the target must succeed on a DC 15 Intelligence saving throw or have the stunned condition until the end of its next turn.
Mind flayers, which are described in the Monster Manual, are created through ceremorphosis, a process that begins with the implantation of an illithid tadpole in the brain of a Humanoid host. Mind flayers have subjected giants to this process in an effort to create larger, stronger mind flayers, but those experiments all ended in failure: a giant's body is simply too large for a single tadpole to take over. Ettins, however, proved to be perfect subjects. An ettin's two brains provide…