Ahri, the Nine-Tailed Fox

The Garden of Forgetting — Ahri, the Nine-Tailed
Fox doesn't untap during your untap step.

Essence Thief — {t}: Gain control of target creature
for as long as you control Ahri, the Nine-Tailed
Fox. When Ahri, the Nine-Tailed Fox leaves the battlefield or becomes untapped, destroy that
creature. It can’t be regenerated.