Jackal's Cage

Jackal's Cage doesn't untap during your
untap step.
{t} Tap any number of creatures you control,
then exile target creature with power less than
the combined power of those tapped creatures
until this card becomes untapped. At the
beginning of each upkeep that creature
perpetually gets -1/-1, unless its toughness is 1.
{1} Untap Jackal's Cage.