Turn Resistance. The zombie has advantage on saving throws against any effect that turns undead.

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.

Multiattack. The zombie Tentacle makes two melee attacks.

Tentacle Slam. Melee Weapon Attack: +6 to hit, reach 15 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage. If the target is a creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the Zombie Tentacle can't attack another target. A grappled creature is autohit by any subsequent attacks.