Essence Backlash

Instant

Counter target creature spell. Essence Backlash deals damage equal to that spell's power to its controller.

"The other guilds will learn the hard way not to interfere with our investigations."
—Bori Andon, Izzet blastseeker

2012-10-01 Abilities that change the power of a creature (such as the one of Collective Blessing) affect only creatures on the battlefield. They won't change a creature spell's power on the stack.
2012-10-01 Essence Backlash can target a creature spell that can't be countered. If Essence Backlash resolves, it won't counter the spell but it will still deal damage.
2012-10-01 If the creature's power is * and it has an ability defining its power, use that ability to determine its power.

mtg.wtf