Cheapest priced copy (Invasion): $0.35 at Card Kingdom, near mint, their price list as of .
Reviving Vapors 
Instant · Uncommon · Ultimate Masters · #205
Reveal the top three cards of your library and put one of them into your hand. You gain life equal to that card's mana value. Put all other cards revealed this way into your graveyard.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.35 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Invasion | 265 | Uncommon | $0.35 | $0.99 |
| Ultimate Masters | 205 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 7 December 2018If a card in a player’s library has {X} in its mana cost, X is considered to be 0.