Cheapest priced copy (Planeshift): $0.35 at Card Kingdom, near mint, their price list as of .
Sinister Strength 
Enchantment — Aura · Common · Planeshift · #54
Enchant creature
Enchanted creature gets +3/+1 and is black.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
1 printing · $0.35 to $0.79 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Planeshift | 54 | Common | $0.35 | $0.79 |