A KH encounter at the Science Building allows a player who passes its check to turn over the top three Mythos cards and choose one. If the chosen card has an open gate as its gate location symbol, that gate is sealed.
This is obviously not one of the types of encounters referred to in the 12/12 FAQ, which allow the closing of a gate, but neither the taking of a trophy nor the sealing of the gate. However, it raises a couple of questions:
(1) Since the gate is sealed, may the trophy be taken? I lean towards yes, since we know that a trophy may even be taken after reading De Vermiis Mysteriis, which only closes a gate without sealing it.
(2) Are the three Mythos cards returned to the top of the deck, or discarded? I feel that this is not like the use of Mythos cards as a location finder (such as for a Rift or a Servant of Glaaki), and is more like casting an Arcane Insight spell, only that the reward is the sealing of a gate rather than the opportunity to re-arrange the cards. Therefore, I returned the cards to the top of the deck in the same order as I found them.
Any feedback on this will be appreciated!