Chaos Crystal

Conduit — (Tap this artifact while casting a spell
to pay for one colored mana of that spell's cost that is
shared by this artifact. You may do this only once per
each colored mana shared.)
When Chaos Crystal enters the battlefield, you
may have it deal 2 damage to any target. If a
creature or planeswalker dealt damage this way
would die this turn, exile it instead. If you don't,
it enters tapped.