Monster Manual, page 173
Stone Camouflage. The grick has advantage on Dexterity (Stealth) checks made to hide in rocky terrain.
Multiattack. The grick makes one attack with its tentacles. If that attack hits, the grick can make one beak attack against the same target. Tentacles. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) slashing damage. Beak. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage.
Forest, Underdark