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