Cheapest priced copy (Fourth Edition): $0.49 at Card Kingdom, near mint, their price list as of .
Clockwork Avian 
Artifact Creature — Bird · 0/4 · Rare · Fourth Edition · #306
Flying
This creature enters with four +1/+0 counters on it.
At end of combat, if this creature attacked or blocked this combat, remove a +1/+0 counter from it.
{X}, {T}: Put up to X +1/+0 counters on this creature. This ability can't cause the total number of +1/+0 counters on this creature to be greater than four. Activate only during your upkeep.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
6 printings · $0.49 to $11.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fourth Edition Foreign Black Border | 306 | Rare | — | — |
| Fourth Edition | 306 | Rare | $0.49 | — |
| Antiquities | 45 | Rare | $11.99 | — |
| Beatdown Box Set | 69 | Rare | $0.49 | — |
| Renaissance | 122 | Uncommon | — | — |
| Rinascimento | 110 | Uncommon | — | — |
3 rulings from Wizards of the Coast
- 4 October 2004If the ability to add counters resolves when there are already the maximum number of counters on it, any counters over the maximum are simply not added.
- 4 October 2004Loses a counter even if it is affected by a Fog-like effect which prevents it from dealing damage.
- 4 October 2004Can attack or block even if it has no counters.