Fireswamp

Fireswamp enters tapped.
When Fireswamp enters, void it's text unless you pay {b}{r} and sacrifice a creature, you may sacrifice an additional creature to untap Fireswamp.
Whenever an opponent attacks you with one or more creatures, untap Fireswamp.
{b/r}{t}: Deal 1 damage to any target or target creature gets -1/-1 until end of turn.
{b}{b}{t}: Create a 1/1 black rat token then put a +1/+1 counter on each rat you control.
It's not that bad. I'm not saying I'd like to build a summer home here, b