Blocking restrictions must be in place when blockers are being declared in the turn based action of the declare blockers step in order to do anything. This means, that granting any form of evasion to a creature can wait until you get priority in the declare attackers step, which happens after the turn based action of attacker declaration in the declare attackers step. So in essence, you can declare attckers, and afterwards make them unblockable, all before blockers are being declared.
However, you cannot wait to see wether your opponent wants to do something before blockers are declared. Or rather you can, but it bears the risk of the opponent not doing anything, which then means that you both passed priority on an empty stack, and thus the game moves on to the next step, which is the declare blockers step.
However, you cannot wait to see wether your opponent wants to do something before blockers are declared. Or rather you can, but it bears the risk of the opponent not doing anything, which then means that you both passed priority on an empty stack, and thus the game moves on to the next step, which is the declare blockers step.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)