2008-08-01
If the permanent is already untapped, you can't activate its {Q} ability. That's because you can't pay the "Untap this permanent" cost.
2008-08-01
The "summoning sickness" rule applies to {Q}. If a creature with an {Q} ability hasn't been under your control since your most recent turn began, you can't activate that ability. Ignore this rule if the creature also has haste.
2008-08-01
This ability affects only creatures that are attacking at the time it resolves. It won't affect creatures that attack later in the turn.
2008-08-01
When you activate an {Q} ability, you untap the creature with that ability as a cost. The untap can't be responded to. (The actual ability can be responded to, of course.)