Cheapest priced copy (Invasion): $0.49 at Card Kingdom, near mint, their price list as of .
Metathran Aerostat 
Creature — Metathran · 2/2 · Rare · Invasion · #61
Flying
{X}{U}: You may put a creature card with mana value X from your hand onto the battlefield. If you do, return this creature to its owner's hand.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
1 printing · $0.49 to $3.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Invasion | 61 | Rare | $0.49 | $3.99 |
One ruling from Wizards of the Coast
- 4 October 2004You can activate the ability in response to itself and get more than one creature card onto the battlefield before this returns to its owner’s hand.