Ok so I'm wondering about cards like Silent Assassin and Osha and when they are allowed to be used, specifically regarding unopposed challenges. The Osha card's text reads "Challenges: Stand Osha to remove her from the current challenge." and the Silent Assassin card's text reads "Challenges: Kneel Silent Assassin to stand and remove 1 of your attacking characters from the current challenge. Then, Silent Assassin is considered to be participating in the challenge as an attacker. "
So I know that you can use Osha in conjunction with another card to boost your attack to get the player to up their defense and then remove her from the current challenge, but what if the challenge goes unopposed?
1. Can my opponent's attacking Osha still be stood up after I declare no defenders or does the challenge automatically resolve because it went unopposed?
Another different example is with the Silent Assassin card (Martell). I know that if my opponent attacks with a non-deadly character, when I use a non-deadly defender, they can then switch out their original attacker with Silent Assassin, allowing them to feint attacks or tack on deadly. Pretty cool. But what if it goes unopposed? Can they declare a military attack with an army card that has 7 attack, then when I let it go unopposed, they switch out the 7 attack card for the Silent Assassin's 1 attack, and then follow up with the same army card doing a 7 power attack?
2. If I declare no defenders can my opponent still switch out their original attacker with Silent Assassin?
3. I guess what I'm asking is if the characters are still 'attacking' or 'participating' in the 'current challenge' when someone declares no defenders. Or is the challenge considered over as soon as the player declares no defenders?
Thanks, and I hope my phrasing was clear enough that my questions aren't confusing.