Soul Crystal (3.5e Spell)

''You chant endlessly until you die. The crystal you were holding falls from your limp hands.''

When the spell is done, you die and your soul is imbued in the crystal. Any creature who touches the crystal must make a Will save or have your soul possess them. You use your own supernatural and class abilities, feats, skills, and mental ability scores, but their physical ability scores, extraordinary abilities, health, and other non-supernatural, non-class traits.

Once per day, the possessed creature may attempt an opposed Will save against you to gain control. If they succeed, they return to their normal state, and you must wait one hour before you can attempt to wrest control back from your host. If you fail, you must wait at least one day between each attempt.

Exorcising you simply requires reducing you (and the host) to -5 health or less.

A creature who successfully saves against your possession is immune to further attempts, and recognizes that touching the crystal caused a risk of possession.

Once you possess someone, the crystal breaks.

Focus: A crystal, worth at least 500 gp.