Securing the Raw Fade
Make a few steps forward and talk to a friendly character Niall (The Circle Tower Raw Fade M, 3). Niall will share his experiences in the Fade - mostly his failed attempts at escaping it. Amidst the gloom and doom, he'll hint about small passages he could not fit through. That is, in essence, your hint for the first section of this quest line: you need to travel through the areas you can reach, and gather more forms in order to access more sections of the Sloth's realm.
Once you're done talking with Niall head towards the nearby portal (The Circle Tower Raw Fade M, 4). Defeat a single demon and talk to the Mage apprentice (The Circle Tower Raw Fade M, 5). During the conversation he'll teach you how to transform yourself into a mouse and you can test this feature right away. Notice that you can also camouflage yourself. This may come in handy while trying to avoid more powerful creatures instead of fighting them.
Turn into a mouse and travel through the mouse hole. You will find yourself in the northern corner of the same central island of the Raw Fade. Be prepared to fight more rage demons. Interact with a nearby statue to gain a codex entry. A fade portal will take you from here to the northwest island. You will pass by a shimmering spirit door on your right that you can't use yet until later, and further on another fade portal that returns you to where you met Niall (The Circle Tower Raw Fade M, 3).
Talking to Niall once again should activate the Fade Pedestal next to him. You won't be allowed to defeat the main demon of this location until you've learned how to transform yourself into a ghost. Once you have that ability in your arsenal use a spirit door located close to Niall (The Circle Tower Raw Fade M, 3). Using this passageway (S, A) will transport you to an arena and you'll automatically start the battle with Yevena (The Circle Tower Raw Fade M, 7). I wouldn't recommend using the golem form here, because she's very agile. Instead remain as a ghost or transform into a burning man. Once you've defeated the demon use the spirit door and you'll end up standing next to the pedestal. Dpn’t forget to go into spirit form to go through (S, B) to fight two wisps and get the Essence of Dexterity.
At this point the Warden can use the pedestal to reach four more sections of the Fade, in any order. The following walkthrough is only one possible sequence, with minimal backtracking. Whether you follow this sequence or devise your own, the objectives are as mentioned above: gather all four forms, kill the five guardians around Sloth, optionally free your companions from their nightmares unless you want to take on the sloth demon alone, optionally grab all possible essences and fonts, and eventually find and face the sloth demon.
Until you obtain all of the forms, your path will be blocked by one of these obstacles:
Mouse holes require the Mouse form
Spirit doors require the Spirit form
Fire barriers require the Burning Man form
Massive doors require the Golem form