It's the Carniphila's boss. It looks and behaves like a Carniphila but it is much stronger. This creature's name is Tiquanda's Revenge, but the symbol ' is not allowed in Creatures' names.
If you are Mage it would definitely be smart to use Sudden Death Runes to kill this. You wouldn't want it to get close to you. The blocker (if there's any) should run it and absorb its distance attacks but not let it come to Melee. If you are a Knight the only and best strategy is to use best weapon and Fierce Berserk. If you are a Paladin use Assassin Stars if possible. Its Healing is extremely fast, much more than Hydra. This is not a regular spawn.