Armor Class 14 (natural armor)
Hit Points 95 (10d10 + 40)
Speed 40 ft.
Senses darkvision 120 ft., passive Perception 10
Languages Deep Speech; see also Brain Dump
Challenge 4
Brain Dump. Whenever the neh-thalggu consumes a brain, it gains the magical ability to speak and understand languages known by the brain's previous owner.
Unusual Nature. The neh-thalggu doesn't require air.
Multiattack. The neh-thalggu makes one Bite attack and two Claw attacks.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 11 (2d8 + 2) piercing damage.
Claw. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) slashing damage.
Extract Brain. Melee Weapon Attack: +4 to hit, reach 5 ft., one incapacitated Humanoid. Hit: 35 (10d6) piercing damage. If this damage reduces the target to 0 hit points, the neh-thalggu kills the target by extracting and consuming its brain.
Mind Blast (Recharge 5–6). The neh-thalggu magically emits psychic energy at one Humanoid it can see within 10 feet of itself. The target must make a DC 14 Wisdom saving throw. On a failed save, the target takes 9 (2d8) psychic damage and is incapacitated until the end of its next turn. On a successful save, the target takes half as much damage and isn't incapacitated.
BAM, p. 39