Nether Sliver

{t}: Turn another target Sliver creature face down as a 2/2 creature. If it doesn't have necromorph, it gains necromorph. Its necromorph is equal to its mana cost.
Necromorph {b} (You may cast this card face down
as a 2/2 creature for {3}. When this creature dies, if it was face-down, you may pay its necromorph cost. If you do, return it to the battlefield face up.)