Several of the Gate Encounter cards involve skill checks stated in such a way that I'm not entirely sure whether they're optional or mandatory.
Gate Encounters with skill checks seem to fall into these categories:
1) "Make a [skill check]. If you pass, [good outcome]. If you fail, [bad outcome]." This is clearly mandatory.
2) "Pass a [skill check] or [bad outcome]." This is also clearly mandatory if I don't want to suffer the negative outcome.
3) "You may make a [skill check] to [flavor text]. If you pass, [good outcome]. If you fail, [bad outcome]." The word "may" clearly makes this an optional check. You can discard the card as if you had no encounter at all.
4) "Pass a [skill check] to [good outcome]. If you fail, [bad outcome]." This is the one I'm hung up on. We've been treating these as mandatory because of the imperative, "Pass a …," but now I'm not so sure. Because it's phrased as "do this to get that," it sounds like I might be able to decide getting "that" isn't worth the risk of the negative outcome. Do I have to attempt these skill checks, or can I opt out of them as if they were "You may make a…" encounters?
Here are some actual examples from the base game:
Blue Other encounter: Pass a Fight (-2) check to lever back the lid of the stone chest. Inside, you find $8. If you fail, lose 1 Stamina.
Blue Dreamlands encounter: Pass a Luck (-1) check to tour the golden spires of Thran, gaining 2 Clue tokens in the process. If you fail, stay here next turn.
Green Great Race encounter: Pass a Sneak (-1)  check to draw 1 Unique Item and return to Arkham. If you fail, your captors are none too kind. Lose 3 Sanity and 1 Stamina.