Essence Backlash

Instant

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

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.
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.