Masters Edition IV

Clockwork Avian

Flying
Clockwork Avian enters the battlefield with four +1/+0 counters on it.
At end of combat, if Clockwork Avian attacked or blocked this combat, remove a +1/+0 counter from it.
{X}, {T}: Put up to X +1/+0 counters on Clockwork Avian. This ability can't cause the total number of +1/+0 counters on Clockwork Avian to be greater than four. Activate this ability only during your upkeep.

Flying
Clockwork Avian enters with four +1/+0 counters on it.
At end of combat, if Clockwork Avian attacked or blocked this combat, remove a +1/+0 counter from it.
{X}, {T}: Put up to X +1/+0 counters on Clockwork Avian. This ability can't cause the total number of +1/+0 counters on Clockwork Avian to be greater than four. Activate only during your upkeep.

Beatdown Box Set

Clockwork Avian comes into play with four +1/+0 counters on it.
Clockwork Avian can't have more than four +1/+0 counters on it.
At end of combat, if Clockwork Avian attacked or blocked this turn, remove a +1/+0 counter from it.
o
X, oc
T: Put X +1/+0 counters on Clockwork Avian. Play this ability only during your upkeep.

Rinascimento

Renaissance

Fourth Edition Foreign Black Border

Fourth Edition

Flying
When Clockwork Avian comes into play, put four +1/+0 counters on it. At the end of any combat in which Clockwork Avian is assigned to attack or block, remove a counter.
o
X, oc
T: Put X +1/+0 counters on Clockwork Avian. You may have no more than four of these counters on Clockwork Avian. Use this ability only during your upkeep.

Antiquities

Flying
Put four +1/+0 counters on Avian. After Avian attacks or blocks a creature, discard a counter.
During his or her upkeep, controller may buy back lost counters for o1 per counter; this taps Avian.