Animated Chest

False Appearance. While the Chest remains motionless, it is indistinguishable from a normal Chest.

Quick Trap. When a creature of medium or smaller opens the chest, the Chest can make the Swallowing Lid action as a reaction.

Rolling Slam. The Chest can use it's movement speed to enter a creatures space, when entered, the creature takes a DC 14 Dexterity saving throw. On fail, the target takes 1d6+3 bludgeoning damage and falls prone. On success, the target only takes half damage and doesn't fall prone.

Destroying the Chest. When the Chest is reduced to 0 hit points, it breaks apart and any creature inside falls out prone in it's place, or the nearest occupied space.

Swallowing Lid. The Chest opens up, target within 5 feet that is medium or smaller takes a DC 14 Dexterity saving throw. On failure, the creature falls inside the chest, the chest is shut, locked, and has the restrained and blinded condition. The creature inside takes 1d6+3 bludgeoning damage when the chest uses up 30ft of movement, but has total cover from outside effects. To escape, the creature must use their action for a DC 16 Strength check, or a creature outside can use their action to unlock the chest with thieves tools (DC 16).