Devil's Ceratophthalmus

As an additional cost to cast Devil's
Ceratophthalmus, you may sacrifice two
creatures. If you don't lose 10 life.
{3}{u}{r}, Sacrifice a creature: Deal X damage to
target creature, where X is the sacrificed
creature's toughness. If a creature dealt damage
this way would die this turn, investigate.
They are surprisingly curious creatures.