Necromancy, huh? How about this?
Girdle of False Life
The Girdle of False Life causes the wearer to gain all the benefits and drawbacks of the Undead type. He is immune to poison, sleep, paralysis, stunning, disease, death effects, and necromantic effects, and he ignores mind-influencing effects (charms, compulsions, phantasms, patterns and morale effects). He is not subject to critical hits, subdual damage, ability damage, or energy drain. He has no Constitution score and is therefore immune to any effect requiring a Fortitude save (unless it affects objects). He loses any Constitution bonus or penalty affecting hit points. He uses his Charisma modifier when making Concentration checks. Negative energy (such as an inflict wounds spell) can heal him, and positive energy (such as a cure wounds spell) can harm him. He is not at risk of death from massive damage, but when reduced to 0 hit points or less, he is immediately killed. He has darkvision with a range of 60 feet. If he is killed while wearing the Girdle of False Life he cannot be raised, but ressurection can affect him.
Of course, if the affects of this belt would have seriously changed the course of the battle, you probably won't be able to use it. Oh well.