Cheapest priced copy (Return to Ravnica): $0.35 at Card Kingdom, near mint, their price list as of .
Essence Backlash 
Instant · Common · Return to Ravnica · #160
Counter target creature spell. Essence Backlash deals damage equal to that spell's power to its controller.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Return to Ravnica | 160 | Common | $0.35 | $0.49 |
3 rulings from Wizards of the Coast
- 1 October 2012Abilities 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.
- 1 October 2012Essence 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.
- 1 October 2012If the creature’s power is * and it has an ability defining its power, use that ability to determine its power.