Text from the Emyn Muil location, The North Stair:

After traveling to The North Stair, move the top card of the encounter discard pile to the staging area. Resolve any "when revealed" effects on that card. Victory 3.

My question is regarding A Test of Will, which reads:

Response: Cancel the "when revealed" effects of a card that was just revealed from the encounter deck.

I just finished a game, and I played it as if A Test of Will cannot be used to cancel the When Revealed effects of a card moved by The North Stair. My thinking is that 1) the North Stair does not 'reveal' a card (the card text does not use the word 'reveal'), and 2) the card being moved comes from the encounter deck discard pile, and not the encounter deck. So both (1) and (2) make it impossible to trigger the response on A Test of Will.

Do you think I played this right?

GS

Yes, you played it correctly.

A Test of Will specifically cancels a "when revealed" effect on a card just revealed from the encounter deck. An encounter card moved to the staging area by The North Stair is not, as you surmised, "revealed from the encounter deck." So, you can't play A Test of Will to cancel the effect.