Blind Senses. The grimlock can't use its blindsight while deafened and unable to smell.
Keen Hearing and Smell. The grimlock has advantage on Wisdom (Perception) checks that rely on hearing or smell.
Stone Camouflage. The grimlock has advantage on Dexterity (Stealth) checks made to hide in rocky terrain.
Spiked Bone Club. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:5 (1d4 + 3) bludgeoning damage plus 2 (1d4) piercing damage.
The degenerate subterranean grimlocks were once human, but their worship of the mind flayers over generations of prowling the Underdark transformed them into blind, monstrous cannibals long ago.