If I kill all my opponent's attackers with Lethal Counterattack, does it end the challenge? Or if my opponent has say...Lord Commander of the Kingsguard as his title, buffing his total power by 3, does it still require me to declare a defender? If I have defenders declared already or declare defenders afterwards does it mean I win the challenge?

Kingsguard said:

Any challenge ends immediately without resolution anytime there are no participating characters. So that's if you play Lethal Counterattack before declaring defenders.

If you declare a defending character before using Lethal Counterattack, the challenge moves on through its resolution. Your opponent, unless has a way to put a character into play as an attacker after Lethal Counterattack, will count 0 strength because he has no participating characters (the multiplayer titles only give strength boosts if you have a participating character). So if you have at least 1 strength, you win the challenge.

Ah, good to know! Thanks.

Saturnine said:

As I know the defending player will not win the challenge if there is no attacking character. In a situation like this, there are no winners for the challenge (and no Responses either).

Miklos said:

The FAQ tells us that, if at any point there are no participating characters in a challenge, the challenge ends without resolution. It says nothing about attacking participating characters.

It's like this:

If all attackers are removed from a challenge before defenders are declared, the challenge ends without resolution. If all attackers are removed from the challenge after defenders are declared, and there is at least one defending character, the challenge is resolved in the usual way (with the defender winning if he has a STR of at least 1).

Which can allow a stark player to do evil and nasty things with core set Robb should your opponents get a little overconfident or forgetful.