Special Equipment: the coffer corpse wields a black mace, a magical mace that grants a +1 bonus to attack and damage rolls made with it (included in its attack). Turn Resistance: The coffer corpse has advantage on saving throws against any effect that turns undead.
Black Mace: Melee Weapon Attack: +5 to hit, range 5 ft, one target. Hit: 6 1d6+3 bludgeoning damage. Choke: Melee Weapon Attack: +4 to hit, reach 5 ft. Hit: 5 (1d6+2 bludgeoning damage and the coffer corpse locks its hands around the throat of the target. The target is grappled (escape DC 12) and begins to suffocate. Until the grapple ends, the target is restrained, and the coffer corpse can't choke another target. In addition, at the start of each of the coffer corpse's turns, the grappled target takes 5 1d6+2 bludgeoning damage.
Feign Death: When a coffer corpse suffers 15 hit points of damage (from any source, even nonmagical), it falls to the ground, apparently destroyed. If grappling a target, it does not release the target. On its next turn, the coffer corpse stands up as a bonus action and resumes its attack. All creatures within 60 ft of the coffer corpse that can see it must make a sucessfull DC 13 Wisdom Saving throw or gain the frightend condition for the next one minute, and must flee if possible.