The Mirror Ritual spell makes whoever attacks you to fight himself as an oponent, just like fighting a mirror. It is both a warrior and a wizard spell, mainly conceived as a spell to enhance your roleplaying.
When you buy the Mirror Ritual spell in the wish shop, you'll be granted with 4 casts. If you already bought it before you get 4 additional casts, and the spell will be in a higher level. You can buy this spell 2 times in the wish shop.
The spell can be cast on a single player per cast, and should be cast by saying the spell words and then the player name, with the option of putting a hyphen (-) in between.