Undead Fortitude: If damage reduces the zombie warrior 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 warrior drops to 1 hit point instead.

Undead Buff. when other undead is 10ft from the Zombie Warroir The Undead gain +10 extra hitpoint and +20 Armor as long they stay in 10ft from the undead warrior. But the Zombie Warrior can roll a wisdom of 35 and other undead gains Rage until their not 10 ft from him or the Rage worn off.

Necrotic Thunder (Long GreatAxe). Melee Weapon Attack: +20 to hit, reach 20ft., one target. Hit:  20 (20d60 + 50) Necrotic damage and (12d40 +40) Thunder damage. If the zombie warrior rolls a 40 on strength the target takes extra 30 damage and stun for short amount of time. 

Rise Grunt (Costs 1 Actions). When his undead allies are dead. The Zombie Warrior got a Necromancer grunt that rise them once again. But they gain +25 extra health and +20 Amor while being Immune magic weapons and Magic spells. Until they are dismiss or been slain.