Rule · Chapter 7
cr:7.3.2
First, defending cards are declared for the attack-target(s). Cards declared this way become defending cards for the attack-target(s) on the active chain link.[7.0.5] Declaring a card this way is not considered playing that card - it does not incur the cost of playing that card, it does not add it as a layer on the stack, and it does not resolve any resolution abilities on that card.