Cheapest priced copy (New Phyrexia): $0.35 at Card Kingdom, near mint, their price list as of .
Arm with Aether 
Sorcery · Uncommon · New Phyrexia · #28
Until end of turn, creatures you control gain "Whenever this creature deals damage to an opponent, you may return target creature that player controls to its owner's hand."
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
1 printing · $0.35 to $0.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| New Phyrexia | 28 | Uncommon | $0.35 | $0.99 |
4 rulings from Wizards of the Coast
- 1 June 2011Only creatures you control on the battlefield when Arm with Aether resolves gain the ability. Creatures you gain control of later in the turn won’t be affected.
- 1 June 2011The granted ability triggers on all damage dealt by the creature to one of your opponents, not just combat damage.
- 1 June 2011The affected creatures keep the ability even if another player gains control of them that turn. If such a creature deals damage to you, the ability will trigger, targeting a creature you control.
- 1 June 2011In a multiplayer game, if an affected creature deals damage to two of your opponents simultaneously, the ability will trigger twice.