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.

Reaction: After Ser Gregor Clegane discards a character using

pillage , place that card in its owner's dead pile.

Then, you may choose and kill a character

with printed cost equal to that card's printed cost.

There is no restriction in the text -- it says "kill a character".

Player B is right.

To invoke the rules a little more specifically:

The "Then..." part of Ser Gregor's ability involves choosing and killing a target character. The only target restriction placed on which character can be chosen is that its printed cost must be equal to the Pillaged card's printed cost. You cannot assume any other targeting restrictions based on the part of the ability before the "Then," and you certainly cannot assume any targeting restrictions based on the Support/Rival mechanic from melee titles.

Note that the reaction was not triggered "against" any player to begin with. Pillage created a triggering condition, and the reaction was triggered against that. As far as the ability is concerned, who owns the card that was Pillaged only matters in that it has to match who owns the dead pile it is placed into. So there really is no connection between "the reaction was triggered against a different player" because the reaction was not actually triggered against a player - it was triggered against a card.

So, there is nothing in the Ser Gregor's text or in the rules of the game that would limit the controller of the character targeted and killed by the "then" part of his ability to the same player who lost the challenge/had a character pillaged from his deck.

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

That's your problem. Instincts about what the rules are have every chance to be driven by motivated reasoning, confirmation biases, and other effects of trying to judge on a "rules as intended" model. While it's often useful to slice-and-dice tangentially related rulings in order to illustrate the first principles of the rules, you should always make sure that you're focusing on illuminating "rules as written." One of the first principles is that character abilities do exactly what it says on the tin.

See also We Do Not Sow, Dagmer Cleftjaw, The Shadow Tower, Roose Bolton, and a plethora of other cards which do specify that their effect targets the losing opponent. Because that clause exists commonly in the game's lexicon, it should not be taken as a first principle of the rules, but rather as a granular aspect of card text that can be included or excluded as a function of the card's power level.

(And lastly, Gregor's effect is Nedly as all get-out. He swings wildly with his ludicrously oversized great sword and clips a spectator who was completely uninvolved in the actual fight.)