Plague gate

Plague gate can be your commander.
Whenever a creature enters the battlefield put
a -1/-1 counter on it. At the beginning of your
upkeep put a -1/-1 counter on each creature with
a -1/-1 counter on it.
{b/g}{b/g}{t}: Proliferate.
{x}{b/g}{b/g}{b/g}{ut}: Destroy X creature(s) with three or
more -1/-1 counters on it. Your opponent loses
X life twice and you gain X life twice.
Slowly it ebbed from the gate, encroaching on Yisl until
there was nothing left