Cheapest priced copy (Fourth Edition): $0.39 at Card Kingdom, near mint, their price list as of .
Backfire 
Enchantment — Aura · Uncommon · Legends · #47
Enchant creature
Whenever enchanted creature deals damage to you, this Aura deals that much damage to that creature's controller.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
4 printings · $0.39 to $4.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fourth Edition Foreign Black Border | 62 | Uncommon | — | — |
| Fourth Edition | 62 | Uncommon | $0.39 | — |
| Legends | 47 | Uncommon | $4.99 | — |
| Renaissance | 24 | Uncommon | — | — |