When can I open a Final Girl's secret (Eyes Only) envelope, and how does the item get used?

Question

Accepted Answer

Open it after you have won a game with that Final Girl. The envelope's card is then shuffled into the Location's Item deck whenever you play her (set aside one fewer Location item first so the weapon is guaranteed to be in the game). The win condition was added to the envelopes after the first printing, so early copies don't show it. In a Lore and Scenario book scenario that lists its own items, don't add the envelope item.