Leodes, The Black Sun

Flying, Deathtouch
Extort (Whenever you cast a spell, you may pay {w/b}. If you do, each opponent loses 1 life and you gain that much life.)
There is no limit to the number of times you may pay Leodes' Extort ability.
When you pay Leodes' Extort ability creatures you control gain your choice of vigilance or lifelink until end of turn.