The grick is a grayish, subterranean snake-worm monstrosity 5 to 8 feet in length, with a sharp, beaked mouth ringed by four clawed, suckered tentacles—in short, the stuff of nightmares. Normally a cavern-dweller, it occasionally ventures aboveground if food is scarce, ensconcing itself in rocky crevices where prey is likely to pass by.
Its Strength and Dexterity are high, in contrast with its average Constitution, so its preferred method of attack is ambush. It’s also primarily nocturnal, on the basis of its darkvision, though not exclusively: it may, for instance, hide in a dark crevice aboveground, yet attack creatures that are outside in the light. At the same time, though, it’s probably more likely to attack around dusk than in the middle of the day. Although it has no Stealth skill per se, it has the Stone Camouflage feature, which gives it advantage on Dexterity (Stealth) checks in rocky terrain. Consequently, it will stick to this kind of area and remain hidden until a target creature draws near, then Attack from hiding, with advantage.