Emiel the Blessed

{3}: Exile another target creature you control, then
return it to the battlefield under its owner's control.
Whenever another creature enters the battlefield under
your control, you may pay {g/w}. If you do, put a
+1/+1 counter on it. If it's a Unicorn, put two +1/+1 counters on it instead. ({g/w} can be paid with either {g} or {w}.)