Extinction Cannon

Spend only {c} on X
Extinction cannon enters with X charge counters
on it.
{t}, remove X charge counters from Extinction
Cannon: Extinction Cannon deals X damage to
target player and each creature that player
controls. Whenever a creature would die, if it has
been dealt damage by extinction cannon this
turn, exile it instead.
{c}{c}{c}{c}: put a charge counter on Extinction
Cannon