3 Questions

[Driryos]

Hey guys,
1- If my non-flying creature blocks another non-flying creature, and my opponent gives his creature flying after i declare the blocker, do i take the damage?
2- If i declare an atacker and tap it, and my opponet uses a spell to tap my atacker, does that spell go on the stack before my atacker is declared, and therefore i won't be able to atack because that creature is tapped? (As a matter of fact, is declaring atackers/blockers a "stack" thing?)
3- If i have Composite Golem and i sacrifice it, and my oponent uses an instant spell to remove from the game, can i sacrifice it again, therefore rendering his spell useless?
Sorry if these questions seem basic, thanks in advance

[Kenji]

1. Flying only prevents non-flying creatures from being declared as blockers. If a creature is already blocking, giving the attacking creature flying doesn't change anything. If your opponent wanted to keep your creature from blocking, they would need to give their creature flying at some point before the declare blockers step.

2. Declaring attackers is a turn-based action, and does not use the stack. If your opponent wants to prevent one of your creatures from attacking,
the very latest they can do so is the beginning of combat step, which is directly before the declare attackers step. If they've waited until you have declared attackers, then your attacking creatures will have already tapped; tapping an already tapped creature won't do anything to stop it, as you might imagine.

Similarly, declaring blockers is also a turn-based action that doesn't use the stack. So, if your opponent wishes to do something to keep your creatures from blocking, it must be done prior to the start of this step.

3. Everything to the left of the colon in an activated ability is the cost. In the case of Composite Golem, whose activated ability is "Sacrifice Composite Golem: Add WUBRG to your mana pool," sacrificing it is part of its cost.

So, by the time your opponent can respond, Composite Golem is in the graveyard and therefore cannot be targeted for destruction.

Furthermore, as this ability is a mana ability, it doesn't use the stack -- the mana is added to your mana pool immediately, before you or your opponent can respond to it. Not that it's relevant to your question; just pointing out that stuff like Stifle or Voidslime would not work, either.