Tithe to the Vile

As an additional cost to cast Tithe to the Vile, sacrifice X creatures. Spend only black mana on
X.
Gain control of X target creatures. Put a -1/-1
counter on each of those creatures. They gain
"When this creature dies, proliferate, then you
draw a card and lose 1 life".
Contracts with Phyrexians contain only ome clause:
Flesh for metal, metal for death, death for true life.