Tapping, Priority and Attacking

[mattdeballer]

We are in the middle of a 10th edition draft and a strange situation has popped up. The active player has a tapped colossus of sardia(without summoning sickness) and an active puppeteer. His opponent has an active Loxodon Mystic. The game proceded as follows.

The active player declared entry into the combat phase. His opponent allowed him to enter the phase. The active player then tried to use his puppeteer to untap his colossus and with priority, declare an attack with the colossus.

What I would like to know is what the required to declare a creature as an attacker. Would the active player be able to untap his colossus and attack with priority, or would his opponent be able to tap it in resposnse?

[Anusien]

You cannot end a phase or step without all players passing priority in succession on an empty stack.  In otherwords, untapping the Colossus is fine, but before you can end the step and go to declare attackers, the opponent has to get a chance to tap it.

Declaring attackers does not take priority.  It happens automatically as a game action (does not use the stack, cannot be responded to) at the beginning of the Declare Attackers Step.  Since you were in the Beginning of Combat Step, you have to get out of that step before attackers can be declared.

[mattdeballer]

Sorry. I guess I was not clear enough. The active player was attempting to untap his colossus during his declare attackers step, and then attack with it. Is this a valid move?

[LordHomerCat]

Negative.

The Steps of the turn (abridged)

Main Phase:
   First Main Phase

Combat Steps:
   Beginning of Combat
   Declare Attackers
   Declare Blockers
   Combat Damage
   etc. etc.

Players receive priority during each of these, and the game only moves to the next step when both players pass in succession with an empty stack.  The Declare Attackers and Declare Blockers steps have special actions.  That is, at the beginning of each step, before either player receives priority, Attackers are declared (or blockers as the case may be).  In order to attack with his Colossus, it MUST be untapped BEFORE he enters the Declare Attackers step.  He can try and do this during the Beginning of Combat step, but since his opponent must receive priority before they move to Declare Attackers, his opponent can then re-tap it.  So, there is no way for him to sneak in an untap and not allow his opponent a chance to respond first.

[mattdeballer]

Thank you very much. That is how I assumed it worked, but what never sure.