If I have Greatjon Umber or some character with the Dragonbone Bow attached can I use such character to participate in the challenge as an attacker against me?

Flintacs said:

Barring any restriction of having your characters participate as attackers against yourself (which Walder Frey seems to indicate there isn't one), I would venture a tentative yes….

But why would you want to?

The reason I ask why is that, even if you have both options available to you, all you are doing is helping your opponent win the challenge. (and I'm assuming you mean Core set Greatjon, as the other one can only be snuck in as a defender). Renown, deadly, and any effects that trigger off your winning a challenge as the attacker won't apply in these circumstances because, even though you have characters participating on the attacking side, you are still considered the defender for the challenge.

stormwolf27 said:

bah. I promise I'm not spamming. I just keep remembering points as I watch the page load after clicking publish. I should reittereate on the subject of renown and deadly…

renown would only take place jumping in one of these as an attacker against yourself if you managed to win the defense on the challenge (and then why would you want to jump them in on the opposing side if you could win anyway?), because they only collect power if they are controlled by the winner of the challenge.

deadly only counts for the attacking side, and you're not adding any more deadly to your opponent's side, though, as the count for number of deadly characters is only characters that each individual player controlls.

There are effects that go off losing challenges (lots of that in Martell), including losing by a specified margin. There are also effects that require all participating characters to share a trait (dragons).Adding an attacker also messes with Joust. As for deadly, you wouldn't be increasing the attacker's deadly count, but your own (which you would also do by using the character to defend).

Khudzlin said:

All valid points. All I saw was "help your opponent win on the attack." The deadly falls short for me, but the rest… I bow to your sneakiness.

Let's discuss the reasons later. Firstly need to know exactly is it allowed or not.

Yes, it is allowed. You can control a character that is participating on the other side of a challenge.

Khudzlin covered most of the common reasons (messing with traits, messing with Joust, and enabling/blocking "win/lose by 4" effects). There are a few more. However, I think you have to credit Stormwolf's reaction, too. The reasons are all situational, and the situations tend to be fairly rare compared to the time-honored strategy of keeping your characters available to work for you.

Thank you, ktom! Good news :)

One more reason is when you need to kneel a character as many times as possible (e.g. Joffrey Baratheon)

Flintacs said:

Is this the "Tales of the Red Keep" Joffrey who stands and claims power when an opponent's character kneels? What effect are you using to get Joffrey into a challenge, particularly since that version of Joffrey is immune to (all) triggered effects?

Yes, it's "Tales of the Red Keep" Joffrey.

I use Dragonbone Bow on him to kneel him as a cost to participate in challenges.

I suppose you'd like to explain that Joffrey would kneel but won't participate as the attacker because of his immunity?

Flintacs said:

Neither would happen, is what I think ktom is trying to say. Dragonbone Bow is a Challenges: *triggered* effect (kneeling Joffrey isn't paying the cost, it's part of the effect of triggering the bow), and thus would not cause Joffrey to kneel in the first place to participate as the attacker in said challenge, due to his immunity.

stormwolf27 said:

Dragonbone Bow

"Attached character gains deadly. Challenges: Kneel attached character to have it participate as an attacker in the current challenge."

Any effect with the text "do X to do Y" implies X as a cost. Kneeling Joff is the cost here.  

Flintacs said:

If you want to interpret it that way and split hairs, ok. The statement still stands that as you are trying to kneel Joffrey, as cost or otherwise, through a triggered effect, he will not do so, as his immunity prevents it.

As I know immunity does not prevent paying costs by kneeling a character. Paying cost is not itself a triggered effect.

Anyway let's wait for ktom's explanation.

Flintacs said:

ok. So let's say you can kneel Joffrey to trigger the bow. Joffrey's immunity prevents him from being put into the challenge by the bow, as it's a triggered effect. Now you have a knelt character that isn't contributing STR or deadly to the current challenge. What does that accomplish?