Dwelling Skull

Zoetic (a noncreature permanent with Zoetic is treated as a creature, except it can't attack or block, and damage isn't removed from it at end of turn.)
Whenever a creature you control enters the battlefield, put a -1/-1 counter on Dwelling Skull and you gain 1 life.
When Dwelling Skull is put into a graveyard
from the battlefield, draw a card for each -1/-1 counter on it.