Powerstone Prison

Enchant player

Enchanted player can't cast more than one spell per turn,
can't lose the game, can't win the game, and their life total can't change.

—
Powerstones were once employed to trap and encase powerful sorcerers and witches who would oppose the Thran empire.
Many such "relics" still remain from that era. Unbothered, unspoiled, and unfettered by time...