Thraben Shadowdancer

Stealth {b}{b} (You may cast this card face down as
a 1/1 creature with skulk for {3}. If this creature deals combat damage or becomes the target of a spell
or ability, you may turn it face up for its stealth cost.)
When this creature is turned face up, destroy target nonblack creature. You gain life equal to its toughness.
"There is more to fear than the dark."