Monastery

{3}{w}, {t}: Create a 0/1 white Monk creature token
with "{t}: Put a conversion counter on target
creature an opponent controls." and "{t}: You
gain 3 life."
If a creature you don't control has five or
more conversion counters on it, you gain control
of it and remove all conversion counters from it.
You can cast this spell only starting in the Castle
Age.