Cheapest priced copy (New Capenna Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Aven Mimeomancer 
Creature — Bird Wizard · 3/1 · Rare · Alara Reborn · #2
Flying
At the beginning of your upkeep, you may put a feather counter on target creature. If you do, that creature has base power and toughness 3/1 and has flying for as long as it has a feather counter on it.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.49 to $2.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Alara Reborn | 2 | Rare | $1.29 | $2.99 |
| New Capenna Commander | 329 | Rare | $0.49 | — |
5 rulings from Wizards of the Coast
- 1 May 2009If the second ability affects a creature, it doesn't cause that creature to lose any of its abilities. It just gives that creature flying as well.
- 1 May 2009The affected creature remains 3/1 and has flying as long as it has a feather counter on it. The effect continues even if Aven Mimeomancer leaves the battlefield.
- 1 May 2009You may put a feather counter on a creature that already has a feather counter on it. Doing so has no visible effect unless some other effect has changed the creature's power or toughness, or caused it to lose flying, since the last feather counter was put on it.
- 1 May 2009If all feather counters on a creature are moved to a different creature, the ability doesn't follow them. The first creature stops being affected by the ability because it no longer has a feather counter on it. The second creature is not affected by the ability because Aven Mimeomancer didn't target it.
- 1 October 2009The effect from the ability overwrites other effects that set power and/or toughness if and only if those effects existed before the ability resolved. It will not overwrite effects that modify power or toughness (whether from a static ability, counters, or a resolved spell or ability), nor will it overwrite effects that set power and toughness which come into existence after the ability resolves. Effects that switch the creature's power and toughness are always applied after any other power or toughness changing effects, including this one, regardless of the order in which they are created.