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.

Multiple Heads.  The zombie has 1d4 + 1 heads it has advantage on saves against being blinded, charmed, deafened, frightened, stunned, or knocked unconscious.

Multiattack. The zombie has 1d6 + 1 arms. it can make as many attacks as it has arms.

Rend. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) bludgeoning damage.

Hideous Rend. The zombie uses all of its hands to target one Medium or smaller creature it can see within 5 feet of itself. The target must succeed on a DC 15 Dexterity saving throw or be grappled (escape DC 15). Until this grapple ends, the zombie can’t make Rend attacks, and the target takes 31 (5d10 + 4) bludgeoning damage at the start of each of its turns. A creature reduced to 0 hit points by this damage is ripped into many pieces.