The question came up over at agotcards, and I'm not sure what the correct answer is:
If I reveal/play a card which gains a trait through a constant effect (e.g. a plot gaining the Power Struggle trait from Stormlands or Campfire Mime gaining the Raven trait from another Raven card in play), would I be able to play a response that triggers off a card with that trait being revealed (e.g. Starve for your King) or played (Samwell Tarly)? I've argued "no", because even though the cards gain the trait as soon as they enter play, they do not have the trait when the action initiates. Others insist that the respective card has the trait by the time you play the response, so it'd be a valid play.
Who has the right of it?
In a possibly related question, if a Valar is revealed, and I use the response of Maester of the Sun ("Response: If it is Summer,kneel Maester of the Sun and discard a card from your hand to save a character from being killed or discarded from play.") and discard Darkstar ("If Darkstar would be discarded from your hand or deck,put him into play instead."), he would come into play during Step 2 of the framework action, correct? I am thinking he would not be affected by Valar because he was not in play in Step 1 when the Kill effect initiated. How wrong am I?