Gate of Sodom

{t}, Sacrifice a creature: Add {b}{b}{b}.
Whenever you activate Gate of Sodom, each
opponent loses 1 life and you gain 1 life.
At the beginning of your upkeep, if you control
no creatures, sacrifice Gate of Sodom.
And there came two angels to Sodom at even; and
Lot sat in the gate of Sodom - Gen 19:1.