Valkyr, Unending Anguish

Whenever you cast a Phyrexian creature or artifact 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 Phyrexian artifact creature.)

At the beginning of each end step, if a Phyrexian died under your control this turn, proliferate.