I am all for curb stomping nice things when the get to uppity, but punishing your players for getting an awesome capstone seems a little... dickish really... I mean if you went through 19 levels of Efreet (with only 10 HD to show for it might I add) you kind of deserve a hug and free wishes... The third option of course being that s/he just lets it all fly, but that is if it is REALLY high-OP.
Regardless this class feature deserves as much regulation as any wish really