I'm pretty sure i know the answers to these, but since inexplicably i'm the one my small game group looks to for rules knowledge, i want to be sure i'm on the right track.
1) "After Varys comes out of shadows, choose and discard 1 Ally character from play." This ability is not a Response and he is an Ally himself, so does he discard himself if there are no other targets?
2) When an effect discards multiple cards from someone's deck, are they discarded one at a time in the same way cards are drawn one at a time? If i discard 2 cards from someone's deck and i have a "Response: after a card is discarded from a player's deck..." can i activate that response once or twice?
3) Varamyr Sixskins: "Put 1 Creature character into play from your hand to return Varamyr Sixskins to your hand. At the end of the phase, if that Creature is still in play, discard it from play." Following the "do x to do y" rule, putting a creature card into play is the cost to return Varamyr to my hand, and if i cancel the effect the cost is still payed. so if i have two duplicates on varamyr, can i put 3 creatures into play, saving varamyr twice before returning the last copy to my hand? And regardless of whether or not Varamyr is saved, the creatures will still be discarded since there is no "then" linking varamyr returning to hand and discarding the creatures?
4) When an event cancels the determination of a challenges winner, that does nothing to effect which characters are participating for the purposes of collecting renown and activating abilities, correct?