Accursed Form

Focusing immense magical energy onto a creature the caster chooses, they force the form of their target to shift over either a matter of 1D6 hours, or 1D6 days, the length of time decided by the caster's own choice. Their form will begin to merge with any bestial aspects the caster sees fit, and the target will have no control over the change. The only way to dispel the curse is for the accursed to kill the caster. Not even a wish spell may remove the curse. The caster can also decide to modify up to 3 of the target's ability scores depending on the bestial form chosen. The target's size can change once in either direction, such as a medium creature being cursed to become a small creature, or a large creature. And finally, in terms of effect, one stipulation may be added, such as an inability to die, removal of speech, blindness or deafness, painful breath, or any other, at the dungeon master's discretion. 

After casting this spell, the caster must rolla D20. On a 10 or lower, they cannot cast this curse again for a month. On an 11 or higher, they cannot cast this curse again for a day. Additionally, a creature already cursed with this spell cannot be cursed again.