You'll have to do some fighting in this phase - mostly golems (where it's a good idea not to keep your party clumped together, or else you'll get whacked by boulders) - and you'll also run into Brogan (#4), but he'll be in the blue phase, so you won't be able to talk to him yet. You'll start out in the normal phase of the thaig. That means it's a good idea to try and remember where the barriers are, so you won't have to wander around as much when you switch phases.
Then as you explore the thaig, you'll discover more colored barriers, and eventually you'll learn that the barriers are linked to different phases of the thaig, and that you'll need to be in the right phase to go through them. When you enter Amgarrak (#1), a green barrier will pop up behind you, preventing your escape.
