Keeper of Shadows

Lurk (Whenever an opponent casts a spell with a
greater converted mana cost than this creature’s
converted mana cost you may put this card onto
the battlefield.)

Whenever a creature with lurk enters the
battlefield under your control you may put a
darkness counter on Keeper of Shadows.
{t} : Remove 2 darkness counters from Keeper
of Shadows. Destroy target permanent.