Tomb of Annihilation
Undead Fortitude. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5+ damage taken, unless the damage is fire or from a critical hit. On a success, the zombie drops to 1 hit point instead.
Slam. Melee Weapon Attack: +3 to hit, reach 5', one target. Hit: 5 (1d8 + 1) bludgeoning damage.