Evolving Dreamscape

{t}, Pay X life: Activate only in response to an
illusion creature leaving the field. Search your
library for an illusion creature with a
converted mana cost equal to or less than
X+the coveted mana cost of the illusion
creature that last left the field this turn and
put it into play.
Nightmares are never still, they collapse upon
themselves creating new horrors from the
pain