Ossein Cage is a new 12-person Trial set in Coldharbour, coming to The Elder Scrolls Online when Seasons of the Worm Cult Part 1 launches.
We've already been introduced to the tropical paradise (with undertones of conflict) of Western Solstice, and this is how you get to the new trial. Yes, Molag Bal’s realm of Oblivion is accessible through a lush island. Your reason for heading over comes via the Fighters Guild, which got info about a valuable magical object created in the Ossein Cage. That object, the Dolorous Cista, reportedly absorbs the pain and suffering created by all the torture the Daedra did on this creepy “torture chamber formed by the bodies of all who died there” and turns it into great magical power.
Sounds like something born out of Coldharbour.
Obviously, you will have to stop this magical object from being used against Tamriel. and it won't be easy because the inhabitants of the Cage “include undead monstrosities, disgusting flesh spawn, and a host of deadly Daedra, including two Titan handlers that disagree on who is better at punishing puny mortals”. That's not all, because the structure itself is also going to try and stop you.
You can head to the full preview for more details on all of the danger and creepy challenges, as well as the rewards, including a brand new mount, the Heart’s Grief Welwa, Kazpian’s Cruel Signet medium armor set, and more.