Skin of Reincarnation (3.5e Equipment)
From D&D Wiki
Skin of Reincarnation: This skin adheres to an individual permanently. After it adheres to someone, whether they want to or not, they reincarnate whenever they die. After 10 uses the skin is no longer functions and can be removed. Anyone wearing the skin is immune to polymorphing effects and cannot forego this immunity for any reason.
Strong Transmutation;CL Variable, see text; reincarnate (caster level 7), contingency (caster level 11), and craft magic arms and armor; the same character need not supply both spells, and only one character needs the requisite feat.; Weight: 0 lb.