The Pound

The Pound enters the battlefield tapped.
{t}: Add {c} to your mana pool
{2}, {t}: Exile target cat or dog and exile target
creature you control. The Pound doesn't untap
during its controllers next untap step.
At the beginning of your upkeep, if you have
exiled over 4 creatures with this land, sacrifice it
and put all of the exiled creatures onto the battlefield under your control.