Cheapest priced copy (Fate Reforged): $0.35 at Card Kingdom, near mint, their price list as of .
Friendly Fire 
Instant · Uncommon · Fate Reforged · #101
Target creature's controller reveals a card at random from their hand. Friendly Fire deals damage to that creature and that player equal to the revealed card's mana value.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fate Reforged | 101 | Uncommon | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 24 November 2014Cards that don't have mana costs, such as land cards, have a mana value of 0.
- 24 November 2014If the card has {X} in its mana cost, X is 0.