45 SINISTER SENTINEL . Someone has painted a red 'X' on the floor of the corridor leading to this room.
In the center of the room is a creature that looks like some insane crossbreed between a giant beetle and a robot. It has a dull gray to black carapace and two glowing green eyes. It is animated by some lost dark magic and will attack immediately.
Grotesque Guard (AC 3; MV 12”; HD 7; hp 34; #AT 4 claws; D 2-7 (X4); SD Fast healing, limited spell immunity; XP 890)
This being is not truly alive, and so it cannot be affected by spells like sleep, charm, and hold. It always takes half damage or no damage from cold-based spells, depending on whether it makes a saving throw. It heals one sixth of any damage it has taken every turn, so it will heal completely from damage if allowed to rest for one full hour. It will not give chase to fleeing adventurers.