Can you play Privileged Position in the interrupt window when losing a power challenge?
The situation I'm thinking of is this... One player has The Red Wedding revealed. The opponent wins a power challenge as an attacker against you and chooses Quentyn Martell (WotN) to be killed. You then trigger Quentyn to kill one of his characters, and he attempts to save that character with Iron Mines. Can you play Privileged Position to cancel Iron Mines, or are you already considered to have lost a power challenge this round?
The Red Wedding
Interrupt: When you win a challenge as the attacking player, choose and kill a Lord or Lady character controlled by the losing opponent. (Any player may initiate this ability.)
Interrupt: When Quentyn Martell is killed, choose and kill a character with a lower STR than his.
Interrupt: When a character would be killed, sacrifice Iron Mines to save that character.
Play only if you have not lost a power challenge this round.
Interrupt: When the effects of an opponent's event or triggered location ability would initiate, cancel those effects.