Lantern of Emerald Will

Flash
You may Exile a Green or Artifact card from
your hand rather than pay this spell's mana cost.
{t}: Add {g}{g}.
{4}{g} or Exile a Green or Artifact card from your
hand; Sacrifice Lantern of Emerald Will:
Counter target Black or Blue spell.
"It's illumination more a treasure than the huge gem.
Even greater when its sudden and unexpected flare of
emerald light fouls a dark and cunning spells."