Undead Fortitude. If damage reduces the zombie to 0 or less 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.

Infect. Upon a successful bite attack, the creature has to make a strength, dexterity or a constitution saving throw with DC 11 to resist the infection. On a fail, the creature loses 1 permanant HP after every long rest and when the creature's HP drops to 0, the creature dies and is emediatly brought back as a zombie. Also, if the creature falls uncontious while being infected, the creature gets 2 death save fails and turns into a zombie upon death. If the creature does not have armor, upon a bite attack it can only make a constitution save. Target can only save themselves after being infected by cutting of the bitten limb before the first long rest or by casting a Greater Restoration spell on themselves.

Horde. When a loud noise is made within 100 ft. of the zombies in an infested area, 3 (1d4 +1) zombies will start approaching the source. If a very loud sound is made, 5 (1d8 + 1) zombies within 200 ft. start moving towards the source at double speed.

Mind Crumbling. After every round while within 30 ft. of the zombie, you have to make a DC 11 wisdom saving throw or take 3 (1d4 + 1) points of psychic damage.

Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage.

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 3 (1d4 + 1) piercing damage and activates Infect.