Cheapest priced copy (Invasion): $0.35 at Card Kingdom, near mint, their price list as of .
Protective Sphere 
Enchantment · Common · Invasion · #26
{1}, Pay 1 life: Prevent all damage that would be dealt to you this turn by a source of your choice that shares a color with the mana spent on this activation cost. (Colorless mana prevents no damage.)
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
1 printing · $0.35 to $3.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Invasion | 26 | Common | $0.35 | $3.49 |