Megalithic Necropolis

Each Supplicant you sacrifice when casting
this spell pays for {3}.
Megalithic Necropolis enters the battlefield with
X Ascension counters on it. At the beginning of
your upkeep, remove one Ascension counter
from Megalithic Necropolis and put a -1/-1
counter on target creature. If you control a
Legendary Demon, repeat this process once.
Sacrifice a Supplicant, {t}: Add {w}{b}{g}