Fairie Bodyshift

Using a tricky magic force you can attempt to change the sex of the target creature, providing the species has a gender to begin with. a willing target causes this spells effect to be permanent.

A unwilling target however can make a Constitution saving throw VS your spell save DC, on a failed save the unwilling target shifts genders to the casters will for 8 hours. the target can re-roll the saving throw every hour to end the spell early.