in the 3e NWN campaign video game by bioware the underdark was reserved for lvl 20+ epic characters due to the insane levels of CR the average monster has down there, almost everything down there can kill you in a variety of horrible ways, I loved how my first venture into the underdark in this game I was like "wait I'm only lvl 4 and I'm already in the underdark getting my daily dose of CBT by mr minotaur"
