Mephala's Realm is called the Spiral Skein

Enodoc

Some text from an ESO lorebook just got added to UESP, and it reveals the true name of Mephala's plane of Oblivion (often called Mephala's Web due to her moniker as the Webspinner and its description in the Imperial Census on Daedra Lords). Not sure if this is in-game currently or if it was datamined.

Introducing "the Spiral Skein":

Rumors of the Spiral Skein by The Derisive Necromite
Mephala! Webspinner! Teacher of the Secret Arts! Queen of the Eight Shadows of Murder! Though others may reign over us, deep in the night we still hear your whisper!
And we do not forget.
In Oblivion you keep your secrets, and the secrets of all those entangled in your webs of subterfuge and semblance. The Spiral Skein is your realm, and like Nirn, in its center is a Tower: the Pillar Palace of Mephala, whose true name is too awful to be uttered.
Spun 'round this pillar, like spokes, are the Eight Strands of the Skein. To each its own space, and to each space its sin.
First is a cavern of plinths and pedestals. Each is a lie, for they pretend to hold up the sky—and the sky is the greatest lie of all.
Second are the chambers of envy, for compared to the cavern above they are cramped and confined, and therefore they hate the cavern.
Third are grottoes alluring and seductive, for their walls and ceilings glow like a million stars that sing a song of love. But the glowing lights are maggots, and the song they sing is decay.
Fourth are the tunnels of fear, for they are eternally dark, and where there is darkness, there is dread.
Fifth are the halls where fair is foul and foul is fair, and every belief is a betrayal.
Sixth is the arena of murder, for ever shall betrayal be followed by murder.
Seventh are the arcades of avarice and appetite, for contained therein are all things mortals would kill or die for.
Eighth is the flaming skein of fury, for as death comes to all mortals, therefore all treasures are lies.
This is the Spiral Skein. The tower is One. The strands are Eight. The lessons are Forever.

Teiji

Beautiful.

So very beautiful.

Thank you.

Enodoc

Kudos to Jimeee who found the book, but this was a great find. I hope ZOS announces the name officially sometime so people can begin to speculate more on what the DLC will include