Gideon's Keep

Gideon's Keep was founded and constructed by the famous adventurer Gideon of Iron Mountain. While fighting the servants of chaos Gideon pushed them back to their source, Demons Pass, where eternal conflict was born.
The keep is what continues to keep demonic forces at bay, and only the most seasoned adventurers travel there. When there is a lack of adventurers to run the keep the nearby nations conscript soldiers to the cause. There are even rumors that prisoners that are proven strong and able may absolve their wrongdoings by serving time at Gideon's Keep.
The only thing separating Gideon's Keep from Demons Pass is an eternally misty swamp. It is said that the foul mist pours out of Demons Pass rotting and killing most life, thus only the hardiness of a swamp may survive.
It is said that the inhabitants of Gideon's Keep have slowly become corrupted by the eternal conflict and foul magic seeps through their lifeblood.
Gideon's keep is well stocked with supplies and can easily last a two year siege, the resiliency was created after the Demons had taken over a significant portion of the keep.
The keep contains all necessary implements for self sufficiency, they grow crops when they can but also harvest cave mushrooms in the keep depths when necessary. There is a famed Elven blacksmith with a workshop capable of crafting weapons, armor, and various mechanics to maintain the keep, and if your request is favorable perhaps his enchanted anvil may grace your metal.
The most famed defense of the keep is a magical ballista of demonslaying sized to kill huge demons, this addition has helped the keep maintain a stronger foothold as it rains deadly timbers down upon the enemy. On the battlefront there are demons strewn about with the giant bolts staking them to the ground.