Argent Witch

{1}{u}{r}, {t}: Tap target creature. It doesn't untap on its controller's untap step. At the beginning of each upkeep, place a -1/-1 counter on creatures tapped in this way. Then, if any of those creatures have power 1 or less, gain control of that creature and remove all counters from it.
The cult of the Argent Moon permeates all of Innistrad. There isn't a single body of government free from its corrupting presence.