Cheapest priced copy (Duel Decks: Knights vs. Dragons): $0.35 at Card Kingdom, near mint, their price list as of .
Seismic Strike 
Instant · Common · Magic 2015 · #280
Seismic Strike deals damage to target creature equal to the number of Mountains you control.
Legal inCommanderPioneerModernLegacyVintagePauper
Not legal inBrawlStandard
4 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Duel Decks: Knights vs. Dragons | 71 | Common | $0.35 | — |
| Duel Decks: Venser vs. Koth | 70 | Common | $0.35 | — |
| Magic 2010 | 154 | Common | $0.35 | $0.49 |
| Magic 2015 | 280 | Common | $0.35 | — |