the objecctives give him three icons, but can he be put into play to defend a challenge using the wall?

also, if aggo bow kills someone, does the challenge go unnoposed and therefore have to lose a 2nd character to mil claim (assuming only 1 defender is declared?)

Zacky Midnight said:

If by objectives, you mean Agendas… it doesn't matter. The Wall puts a character into play knelt as a defender into the challenge - a character doesn't require an icon to participate in a challenge, only to be declared an attacker/defender in the regular framework action. So yes, you can put him into play using the wall and you could do so even if you were running No Night's Watch agendas, and even if your oppontent had "Desolate Passage" revealed and you had already declared one defender.

As for the second question, if the opponent declares a single defender and you kill him using aggo's bow (And he's not saved etc), the challenge continues as normal just as if you'd killed/removed defending characters from the challenge under any other circumstances. As he has no defenders, the challenge is unopposed, and you'll still get regular military claim and the power for an unopposed challenge.