Undead Fortitude. 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.

Corrosive. Any nonmagical weapon made of metal or wood that hits the zombie corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls. If its penalty drops to −5, the weapon is destroyed.

Multiattack. The zombie attacks with its breath and either its bite or slam.

Slam. Melee Weapon Attack: +3 to hit, reach 10 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage.

Bite. Melee Weapon Attack: +3 to hit, reach 5ft., one target. Hit: 5 (1d6 + 1) piercing damage plus 3 (1d4) acid damage. On a hit the creature must make a DC 6 Constitution saving throw or be zombified gaining a point of exhaustion at the start of every new day for 6 days until the final point makes the creature fully undead. The effect can be removed with a Lesser Restoration or Greater Restoration if the creature is fully undead.

Acid Breath (Recharge 5–6). The Zombie vomits acid in a 10ft cone. Each creature in that cone must make a DC 13 Dexterity saving throw, taking 4 (1d8) acid damage on a failed save, or half as much damage on a successful one.