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.

Longsword. Melee Weapon Attack: +4 to hit, reach 5 ft., 1 target. Hit: 7 (1d8 + 3) Slashing damage. 

Bastion. The zombie raises its shield and plants its feet to give itself 10 temporary hitpoints and advantage on dexterity saving throws.

Forced Fortitude. The zombie can kill itself as a bonus action. Upon succeeding a DC 10 constitution save the zombie rises on its next turn with 1d8 +1 hit points

Shield. Once per turn as a reaction, the zombie can raise its shield and add a +2 to its AC or dexterity saving throws to avoid a hit possibly.