King Bymon, When he ask you a question, SAY NO. He'll tell you to go to the Desert Of Destitution.
This first meeting is optional.
The Desert goto the bottom of the destert, 1 step from the edge/wall, going counter clockwise. At top go right down right down, to get to the "Pit".
After getting the Candle of Darkness, talk to him again, this opens the path.
At the far right of the room with Bymon, go straight up to get to the hidden path.