He runs The Yawning Portal Inn and considers himself the self-appointed gatekeeper to Undermountain. He is known for having explored Undermountain.
I'll give you a free flagon of ale if you don't talk to me about the weather.
-Durnan
Abilities
Durnan fought with either a dagger, a handaxe, or a greatsword (which could be seen hanging behind the bar) and did so with tremendous physical strength. However, he also kept at least one secret magical weapon on his person, while at the same time carrying a mundane one in the open.
He was the owner of a very sturdy body. However, he was also very wise and knowledgeable to the point of being considered a "thinking man's barbarian". He knew a lot about various weapons and martial arts, including from Kara-Tur and the Hordelands. While he had no spellcasting abilities of his own, he was knowledgeable enough that he could recognize the properties of a lot of spells.
History
Durnan was born in the remote North in 1283 DR. He started adventuring with Mirt when the two were still quite young.
Durnan was known as "The Wanderer" because that was precisely what he spent his youth doing: wandering around seemingly aimlessly, killing monsters.
In 1302 DR, Durnan and Mirt went into Undermountain and managed to come back not only alive but also rich. This was one of the first instances of somebody surviving a foray into Unknown's property. He used the looted wealth to tear down the remnants of Halaster's Hold to build The Yawning Portal inn. He spread the information about the size and the wealth that could be found in Undermountain. Combined with the good location, on which he built his inn, it guaranteed him his living by selling equipment to people who wanted to enter the dungeon too. Durnan retired as an adventurer. The reason for this was that he made a promise to his girlfriend at that time to come back to her when he managed to become rich.
Durnan and Mirt have managed to live unnaturally long lives possibly due to some of the strange magics that can be found in Undermountain. But no one really knows how.