Hello,

playing today a couple of games we came upon a question:

Lets say someone has The Power of Blood plot card and has two charcters in play. One noble and one that isnt. If that player looses a military challenge can choose/name the noble character to die in order to "fizzle" the "kill" effect (and save the other)?

thank you!

No, you cannot.

"Cannot" in AGoT basically means "Don't even try". So, you would not be allowed to choose the noble character for claim.