Cheapest priced copy (Battle for Zendikar): $0.35 at Card Kingdom, near mint, their price list as of .
Roil's Retribution 
Instant · Uncommon · Battle for Zendikar · #45
Roil's Retribution deals 5 damage divided as you choose among any number of target attacking or blocking creatures.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Battle for Zendikar | 45 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 25 August 2015You choose how many targets Roil’s Retribution has and how the damage is divided as you cast the spell. Each target must receive at least 1 damage.
- 25 August 2015If some, but not all, of the targets become illegal by the time Roil’s Retribution tries to resolve, the original division of damage still applies, but no damage is dealt to illegal targets. If all the targets are illegal, the spell won’t resolve.