Cheapest priced copy (Ravnica: Clue Edition): $0.35 at Card Kingdom, near mint, their price list as of .
Pit Fight 
Instant · Common · Ravnica: Clue Edition · #202
Target creature you control fights another target creature. (Each deals damage equal to its power to the other.)
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
3 printings · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Ravnica: Clue Edition | 202 | Common | $0.35 | — |
| RNA Guild Kit | 93 | Common | $0.39 | — |
| Gatecrash | 223 | Common | $0.35 | $0.79 |
2 rulings from Wizards of the Coast
- 24 January 2013The second target of Pit Fight can be another creature you control, but it can’t be the same creature as the first target.
- 24 January 2013If either target of Pit Fight is an illegal target when the ability tries to resolve, neither creature will deal or be dealt damage.