Altar of the fanged

Whenever you pay life, put a sacrifice counter on
Altar of the fanged.
Pay 4 life- add one mana of any color to your
mana pool. Then, if there are four or more
sacrifice counters on Alter of the fanged,
remove them all and create a 4/4 black
serpent creature token with deathtouch.
This ability costs one less life for each
sacrifice counter on Altar of the fanged.
Activate only as a sorcery.