Multiattack. The dragon makes two attacks, one with its claws and one with its tentacles.
Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 11 (2d8 + 3) slashing damage.
Tentacles. Melee Weapon Attack: +5 to hit, reach 10 ft., one creature. Hit: 8 (1d10 + 3) psychic damage. If the target is Medium or smaller, it is grappled (escape DC 13) and must succeed on a DC 10 Intelligence saving throw or be stunned until this grapple ends.
Extract Brain. Melee Weapon Attack: +5 to hit, reach 5 ft., one incapacitated humanoid grappled by the dragon. Hit: 24 (6d8) piercing damage. If this damage reduces the target to 0 hit points, the dragon kills the target by extracting and devouring its brain.
Mind Blast (Recharge 5–6). The dragon magically emits psychic energy in a 30-foot cone. Each creature in that area must make a DC 13 Intelligence saving throw or take 15 (3d8 + 3) psychic damage and be stunned for 1 minute. A creature can repeat the saving throw at each of its turns, ending the effect on itself on a success.
Description
One of the few consolations available to those who must contend with a mind flayer colony is the limit of its reach, which spreads only as far as the influence of the colony’s elder brain. But this small solace withers away when a colony manages to capture a dragon. Teams of mind flayers bind the dragon, which is subject to a gruesome transformation as the tadpole infects and transforms dragon’s brain and body. A brainstealer dragon is the nightmarish result.
Credit to Dungeon Dad
Comments