Undead Fortitude. Zombies do not require air, food, drink, or sleep. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant 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 ft., one target. Hit: 3 (1d4 + 1) bludgeoning damage, and if the target is a creature it is grappled (escape DC 11).

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature the zombie is grappling. Hit: 3 (1d4 + 1) piercing damage and the target must succeed on a DC 13 Constitution saving throw or contract the zombie rot disease. The diseased target can’t regain hit points, and its hit point maximum decreases by 7 (2d6) for every 24 hours that elapse. If the disease reduces the target’s hit point maximum to 0, the target dies and returns to life as a zombie in 1d4 hours.