"How far? Ye’ll know ye’ve found Malver’s Way when ye sees the Arch."
Gnomes, fascinated with magic, tried to find a way to safely access it, and instead wound up addicted in the deadliest way.
Thaumatechnology - in a world where straight magic has an unnerving tendency to get the user killed, either by magical catastrophe or by being lynched by an upset mob, this is a much safer form of magical use… Even if it does occasionally explode.
A fey spirit masks itself as a bee which investigates all who travel within a specific section of the forest. Any the bee finds worthy are allowed to see the hidden opening into the fey kingdom, just off of the trail. Any deemed unworthy see only the bee, buzzing around around them momentarily before moving on.