I am stuck in the Vale of Shadows. I am in the main chamber where you needed the yellow gate key to enter. I fought the skeleton leader named "Mytok" or something Ive explore the whole area and there apears to be another hallway on the left side but I cant get into it. How do you get into that hallway?

The level is symmetrical so target the floor on the "left" side (yes I already read your post about you making a type-o) and then click on the exact same spot on your "right" side. You'll walk right into the new corridor that is hidden by shadows and walls. Fooled me too.