Say you have a card that says something to the effect of "After an intrigue plot is played, choose any opponent character in play and discard him."

You could do that at any point in the game (after the intrigue card is played) couldn't you? Seems like you should be able to as long as it's during whatever point in the phase a response is allowed.

No.

As it says in the FAQ, "You can think of opportunities as 'gates' that open up, allowing you to play specific responses during an action window. ... These opportunities (or "gates") stay open until Step 6, when the action finally ends and the action window closes." So, using your example, your only opportunity to respond to a plot being revealed (not entirely sure what "playing an intrigue plot" would be...?) is in the action window in which the plot is revealed. Once that window has closed, you're not really responding any more. Playing a response 3 phases later is like thinking up the perfect comeback to someone's comment later that night.

Now, if instead of a Response, you had a standard action that said something like, "Any Phase: Choose and discard an opponent's character. Use this effect only if your current plot has the Intrigue Gambit trait," it would work more like what you describe.

I see. Thank you!