Were-Curse (3.5e Spell)

You say something spiteful, and nothing special happens for days.

Choose one type of magical beast with a Challenge Rating no greater than your caster level. Every full moon, the affected creature transforms into that creature for 1 hour. All attributes of the creature other than current health percentage are changed; the creature acts like a typical magical beast of that type would, and does not remember what happened.

A Were-Curse cannot be removed with anything short of a wish or miracle, or a quick visit to some special fountain on a good-aligned plane.