Clockwork Steed

Text:

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

Rulings:

• 10/4/2004 Loses a counter even if it is affected by a Fog-like effect which prevents it from dealing damage.
• 10/4/2004 Can attack or block even if it has no counters.
• 10/1/2008 When Clockwork Steed’s last ability resolves, you can choose to put fewer than X +1/+0 counters on it.
• 10/1/2008 If Clockwork Steed has four or fewer +1/+0 counters on it when its last ability resolves, it can wind up with a maximum of four such counters on it. If it has four or more +1/+0 counters on it, the ability will have no effect.