The Well

If my opponent wins the story The Well (Secrets
of Arkham F60), but both of us have no other
already won stories in our won piles does the
second effect still trigger and destroy all the Day
and Night cards in play?
No. The Well has an If/Then statement,
which requires the first part (each player
shuffling 1 won story, other than The
Well, back into the story deck) before the
second effect will trigger (destroying all
Day and Night cards in play).

While there is at least 1 Conspiracy card in play, Savio Corvi gains, "Night, .... Savio Corvi is immune to non-Day card effects."

"The Well" attempts to destroy all Day/Night cards, but it is not itself a Day card. So, whenever he is a Night card, Savio is also immune to the Well, and all of its effects. Ergo he is not destroyed.

Do both players need to have a story for a players to use the first part of the card? I have always considered it as a "comeback" story. Your opponent has one story, you have none. You win this - opponent shuffles his story back, and you don't (because you only have the well). Have I been playing it wrong?

I assumed both players needed at least one won Story for this to be trigerrable.