So I'm sure this has been asked already and if Tzumainn was still up I would have searched for the answer there, but does Brienne's ability, which says "While Brienne is participating in a challenge, opponents cannot trigger effects." work against cards like True Power (which cancels the determination of winner a power challenge) and Red Vengeance (which switches claim fulfillment) if you attack or defend with her? She is still participating in order to be determined the winner right?

Also would other responses, like the "after you win/lose a challenge" get by her effect (specifically Vipers Rage or Seductive Promise)? Is the challenge over by the time those cards are played so she is not participating anymore?

cha0s said:

Brienne does prevent all of the effects you mention (as long as they are triggered by a player and not passive). The opportunity to play responses to determination of challenge winner, claim, passives keying off of challenge result, etc. is during the Responses step of the Challenge Resolution Framework Action Window (or earlier in the challenge for stuff cancel effects like Red Vengeance and True Power). Brienne is still participating in the challenge until the end of that step.