Sepulchral Cove

Sepulchral Cove enters the battlefield tapped
with a bone counter on it.
{t}, Pay 1 life for each bone counter on this land:
Add {c}. If you paid four or more life to activate
this ability, add {b}{b} instead.
Whenever a nontoken creature you control would
die for the first time each turn, you may exile it
instead. If you do, untap Sepulchral Cove if it's
tapped and put a bone counter on it.