I have a question about a situation which came up while we were playing a melee game last night. We had three players (Player A, Player B, and Player C). Player A and Player B had titles which made them rivals, and Player B's title also supported Player C.
Player B used Ser Gregor Clegane in a challenge against Player A, and Player B won. Ser Gregor's reaction occurred, and Player A's deck was pillaged, revealing a character. Ser Gregor should then be able to do the second part of his reaction, killing another character of equal cost.
Player B used this to kill a character from Player C instead of Player A.
I need to clarify this, because I felt this was a wrong way to resolve this for two reasons: one, the challenge was not made against Player C (because the title stopped Player B from challenging Player C anyway), and two, the reaction was initially triggered on a different player, and my instinct says that once started, a reaction must be triggered on a single player unless it says otherwise. I can't find anything in the rules one way or the other, and this is likely to continue happening, as Player B believes this is a convenient way to kill characters of a player that they are unable - or not strong enough - to challenge themselves because of titles or that player's strength.
Can someone please help me find a ruling that either confirms this is right, or confirms it is not? Thank you.