Sept/oct '23 Lite challenge: "The serpent valley"

[Simkin]

I would guess it's the S-shaped valley that the V points to and that it would in gameplay involve a rollable table for if people explore other places, for random encounters and hints.

It is not that, but you are right with the idea of dangerous enconters in others locations. The idea is that if the group goes around randomly, will alert the clerics of Vecna. If the heroes cannot attack by surprise, will not have any chance of destroy the cult.