The Devil's Way

A poorly (if at all) maintained path through the woods and hills of the southern Pikespine Peaks. Unused for a hundred years, and seldom used for a hundred before that, this broken, rocky path meanders through thick copses of woods, right by a couple of graveyards and a Progenitor King's barrow (heading from west to east). They say the entire gulch there is haunted, and enough people believe it to be true that this particular stretch of the road has been unused for longer than anyone can remember.¹
Since that part of the road must be passed, an infamous kobold nest must be dealt with. A slash in the mountainside opens into a cavern of immense proportions that houses an entire kobold township. They have abstained from attacking any established settlements or the like, making them too small of a problem for the The High Kingdom to make a priority. Recent intelligence reports tell of a leader, some messiah-like figure, that has organized and focused their raiding much more precisely. The High King's Seat seat would pay well for information about this leader.
Meandering past that stretch of the road, farther to Craysilt's east, the real hills begin, and one will need to crest a highlands pass and scale the slope beyond. There were wide, shallow steps and a sturdy handrail made of a huge gauge of rope at one point in history, but repurposing and time have eroded both so far as to be no real help. The remnants and ruins of the very road, however, are a testament to the Progenitor, human's ingenuity and handiwork, and every so often, one will come across the odd rail post, still poker straight and covered in indecipherable runes as they repel down the steep slope those stairs had once tamed.
Once there, the real fun will begin. The ancient mine entrance, leading 'safely' under the mountain, is a complete unknown, except for one fact: no one has ever emerged, that we know of. They have all, however, been coming in the other direction...from east to west. This leads Cass Elliot to believe travelling through it from west to east will be just fine. Cass has studied Progenitor, human artifacts and mysteries her entire life, and feels quite confident that west to east will be challenging, but absolutely doable, for the adventurers. She has estimated that only one of you would die under the mountains.
Defend yourselves well, remember to keep stealthy, gather information before making any brash moves. The servants and slaves of the The Necrodruid are everywhere in those mountains, it is why I believe going under them is your best choice. It was a mithril mine at some point in ancient history, pre impact even, if you believe in that myth.
Each night, it will be important to set watches. Some folks believe that their meditations and trances can keep them safe during a watch, but we assure you, those that will be hunting you once they discover you and your mission can bypass them with ease. Be vigilant, be ready, be worthy of victory! 
Under the mountain will be a maze of branching tunnels and offshoots. These points can be dangerous; be careful of ambushes. You must keep to the path! It is marked on the floor with an aquamarine line. You must keep to the aquamarine line! It is imperative. Aquamarine is the safest way under the mountains. Remember this! If you lose the aquamarine path, backtrack until you have found it. Do not continue blind!
Sleep well before venturing into Greendell valley itself. You will be unable to rest within the spore-poisoned area of the dell itself. Do not spend more than twenty-six hours...one day...within spore poisoned regions, or exhaustion will begin to overtake you quickly. Be wary, and if you are forced into spore polluted places, find the pockets and currents of clean air. Sleep when you can, it will be a precious resource to you, sleep will. Do not sleep within a spore-filled area! I repeat the invective because it is that important.

Geography

A wandering tunnel through the Pikespine Peaks, leading to the other side of the mountain range and access to Greendell Valley.

Fauna & Flora

Known challenges:

• We know of at least one Ghaunadan
• Brain Spiders have infested some of the chambers of the passage...stay on the aquamarine path!
• Carrion Crawlers have made a nest somewhere within
• There is a manticore that has been seen flying around near the exit of the cave system. Take care.
• There have been reports of Uchuulon, which may indicate a mind flayer colony. Avoid this! Stealth and secrecy are your friends!

History

Originally a mithril mine, it was abandoned a millenia or so ago and has since become the abode of wandering nightmares...

Tourism

Seriously?

Alternative Name(s)

"Satan's asshole" ; "Mordin Mine"

Type

Mountain Pass

Location under

Feynor

Owner/Ruler

High King Artemis ("Artie") Grey

Ruling/Owning Rank

High King

Owning Organization

Unified Kingdoms of Greysilt

Contested By

• The Dwarven East Aidni Company