I was in a local tournament this weekend in which a ruling dispute came up. The scenario was that I was being attacked by 2/1 First Strike creature. In response, I activate Mishra's Factory (2/2) and block. I wait for damage to go on the stack and tap the Factory to give it +1/+1 before damage is assigned. Thus, I thought the 2/1 deals two damage first and then the surviving Factory deals its 2 damage.
That is the rule how I understood it. The local unaccredited judge said that the first stiker gets priority and that the Factory doesn't get to deal damage. I asked him why. He gave me some B.S. answer that a tapped creature doesn't deal damage. I knew this was false under 6th edition rules. So can someone tell me if I am right and please explain exactly the rule of first strike?
The judge was incorrect. Tapped creatures do deal damage, and you can respond to first strike damage by tapping to make your factory a 3/3. Your factory doesn't assign it's damage until after that 2 damage resolves however. When it does assign damage, it will assign 3.
Combat goes as follows - after each step is a chance for instants:
(1) Beginning of combat
(2) Declare attackers
(3) Declare blockers
(4) First strike damage goes on stack
(4A) first strike damage resolves
(5) regular damage goes on the stack
(5A) regular damage resolves
(6) End combat
SO first strike damage is just like regular damage, except (wait for it...) it happens first. So the creatures which have been first-struck are already dead - if they're going to die - before they get a chance to deal damage. If a creature is forced to regen, it's removed from combat and deals no damage.
Phew. So - yes, the local judge was wrong. No matter when (after it is declared as a block) the fatory becomes a 3/3, it still deals 3 damage (as long as the first strike damage doesn't resolve before you make it a 3/3). Tapped blockers still deal damage.