Undead Fortitude. If damage reduces the Zombieborg 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 5 hit points instead.

Cyborg Regeneration. At the beginning of the Zombieborg's turn, it regains 15 hit points and cannot be killed until this effect is mitigated in some way,  through acid or fire damage.

Necroes Regen. Any necrotic damage dealt to the Zombieborg, heals it and fixes any damage dealt to it. 

Multiattack. The Zombieborg makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 29 (2d12+7) piercing damage plus 7 necrotic damage

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 20 (2d6+7) slashing damage plus 7 necrotic damage.

When hit points drop below half the Zombieborg gains access to Raging Maul as both a reaction and an action. Raging maul replaces bite.

Raging Maul. Melee Weapon Attack: +11 to hit, reach 5ft., one target. Hit 15 (2d12 +7) piercing damage + 15 (2d8+7) slashing damage plus 7 necrotic damage.