Adamantine plating. Any critical hit scored against the Adamantine Soulmomunger is treated like a normal hit. 

Automated Repairs. The Soulmounger regains ten hit points at the start of its turn if it has at least one hit point left. This ability doesn’t activate if the Soulmomger has taken acid damage sense its last turn. This ability ignores the effects of the Soulmounger’s antilife feild.

All Seeing Sensors. The Soulmounger can see in all directions. Magical darkness dose not impede on the Soulmounger’s darkvision. The Soulmounger can see invisible creatures as if the where not invisible.

Soul Stealer. A creature who is killed by the Soulmounger has its soul removed from it and shunted directly to the phylactery of the lich the Soulmounger serves. Once the soul has been removed the only way to revive the creature is to cast True Resurrection on the body within 1d4 minutes of when the creature was killed. Otherwise the creatures soul is destroyed fueling the lich’s undead immortality and the creature cannot be revived by any means.

Spider Climb. The Soulmounger can climb difficult surfaces including vertical surfaces and on ceilings with out needing to make an ability check.

Seige Monster. The Soulmounger deals double damage to objects and structures 

Multiattack. The Soulmounger makes three attacks two with its Rend and one with its Antilife Ray.

Rend. Melee Weapon Attack: +8 to hit, reach 10 ft., 1 target. Hit: 13 (1d12 + 6) slashing damage plus 8 (1d8 + 4) necrotic damage

Antilife Ray. Ranged Spell Attack: +7 to hit, range 120/300 ft., 1 target. Hit: the targets hit point maximum is reduced by 5 (1d8) this effect can be cured via a Remove Curse spell or similar magic.

Antilife Field (recharge 6). The Soulmounger created a field of necrotic enegery around itself in a twenty foot radius centered on itself. Creatures within the sphere cannot regain hit points or benefit from healing magic such as that of a Greater Restoration, Remove Curse, or Revivify spell. This ability dose not cancel out natural or class abilities such as the paladins Devine Health ability however natural or class abilities cannot regain hit points so the fighters Second  Wind ability would have no effect. This ability lasts until the start of the Soulmounger’s next turn.