Necronom IV

Whenever you cast a Xenomorph creature spell, incubate X, where X is that spell's mana value.
(Create an Incubator token with X +1/+1 counters
on it and "{2}: Transform this artifact." It transforms
into a 0/0 Xenomorph artifact creature.)
At the beginning of each end step, if a
Xenomorph died under your control
this turn, proliferate.