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.

Hoard. The zombie has advantage on an attack roll against a creature if at least one of the zombie's allies is within 5 feet of the creature and the ally isn't incapacitated.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) piercing damage and if the damage reduces the target to zero hit points and they die then they rise 1d4 rounds later as a zombie (reworked).

Broken Sword. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) slashing damage.