Cheapest priced copy (Eternal Masters): $0.35 at Card Kingdom, near mint, their price list as of .
Seal of Strength 
Enchantment · Common · Nemesis · #115
Sacrifice this enchantment: Target creature gets +3/+3 until end of turn.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
3 printings · $0.35 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Eternal Masters | 184 | Common | $0.35 | $0.79 |
| Nemesis | 115 | Common | $0.35 | $7.99 |
| The List | EMA-184 | Common | $0.35 | — |