Gatekeeper (5e Creature)
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Large aberration, lawful evil
Enclosing Shell. The gatekeeper can open or close its shell as a bonus action. While closed, the gatekeeper's AC is 20, and it gains resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks, but its flying speed is reduced to 20 feet.
Innate Spellcasting (Psionics). The gatekeeper's innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components:
Siege Monster: The gatekeeper deals double damage to objects and structures.
Multiattack. The gatekeeper makes two attacks with its tentacles.
Tentacle (Only while the gatekeeper's shell is open). Melee Weapon Attack: +4 to hit, reach 10 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage and the target must succeed on a DC 15 Wisdom saving throw or take 9 (2d8) psychic damage.
Eye Ray. Ranged Spell Attack: +7 to hit, range 60 ft., one target. Hit: 9 (2d8) force damage.
Close Shell. If the gatekeeper takes damage while its shell is open, it can close its shell.
A distant relative of the Beholder, Gatekeepers make their homes in the Underdark, acting as wandering hunters.