Lux Artillery (Extended Art) [Phyrexia: All Will Be One Commander]

Whenever you cast an artifact creature spell, it gains sunburst. (It enters the battlefield with a +1/+1 counter on it for each color of mana spent to cast it.)

At the beginning of your end step, if there are thirty or more counters among artifacts and creatures you control, Lux Artillery deals 10 damage to each opponent.