Clockwork Beast

'This creature enters with seven +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 seven. Activate only during your upkeep.