Gate of Chaosium

A gate of powerful and aggressive chaos.  Once the site of an experimental station of Elves.  These mages sought to use, but also rule this plane that was antithecal to them.  In the end it corrupted them.  Sealing it they abandoned it.  
When Phan the Magnificent and Rolen Synnix found those ancient chambers they spent many week under its influence, many in their party were physically altered, and all felt the mental effects of it.  After many labors they shut down the gate, but also found the Orbs of Chaos.  These Orbs were the vital item needed to counteract the Three Gates.