Cheapest priced copy (Duel Decks: Knights vs. Dragons): $0.35 at Card Kingdom, near mint, their price list as of .
Claws of Valakut 
Enchantment — Aura · Common · Worldwake · #75
Enchant creature
Enchanted creature gets +1/+0 for each Mountain you control and has first strike.
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
2 printings · $0.35 to $2.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Knights vs. Dragons | 72 | Common | $0.35 | — |
| Worldwake | 75 | Common | $0.35 | $2.49 |