Cheapest priced copy (Fifth Edition): $0.35 at Card Kingdom, near mint, their price list as of .
Clockwork Steed 
Artifact Creature — Horse · 0/3 · Uncommon · Fifth Edition · #357
This creature enters with four +1/+0 counters on it.
This creature can't be blocked by artifact creatures.
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 inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
2 printings · $0.35 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Fifth Edition | 357 | Uncommon | $0.35 | — |
| Homelands | 103 | Common | $0.35 | — |
4 rulings from Wizards of the Coast
- 4 October 2004Can attack or block even if it has no counters.
- 4 October 2004Loses a counter even if it is affected by a Fog-like effect which prevents it from dealing damage.
- 1 October 2008When Clockwork Steed's last ability resolves, you can choose to put fewer than X +1/+0 counters on it.
- 1 October 2008If 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.