Beyond the door, you eventually came upon a kobold sorcerer, and a powerful stone of some sort. The stone seemed to have the ability to grant powers to those who used it, but at a terrible toll. Perhaps this explains the unusual strength of the kobold tribe, coupled with their aggressiveness.
After great debate, Zastaph activated the stone, using a rod gained from the kobold sorcerer. Doing so opened a portal. Stepping through it, you found yourself in a land of stone that emanated great evil. You have just defeated some stone creatures, and are ready to press onward.
