As a sort of precursor organization to the Mages Guild, the Psijic Order helped develop many forms of magic, including those found in the Mysticism school in pre-Skyrim Elder Scrolls games.
Summerset Isle hasn't featured in an Elder Scrolls game since before I was born, back in 1994's The Elder Scrolls: Arena.
By the decree of Queen Ayrenn, Summerset Isle is now open to foreigners, but a Daedric threat looms over the breathtaking home of the High Elves.
A new skill line that can be learned from the Psijic Order, a new joinable order. Reunite with old friends, forge new alliances, and work together to unravel a conspiracy that threatens Tamriel's very existence. Once you've geared up, you can attempt the new PvE challenges, including new Delves (sort of a story-focused dungeon which can be tackled either solo or in a group), boss encounters, and a new 12-player Trial (ESO's equivalent of raids). Pre-purchasing will also net you the Queen's Bounty Pack, with the Court of Bedlam costume, a Pocket Salamander pet, treasure maps, a Psijic Vault Crown crate, and experience boosters, plus a digital copy of the Morrowind DLC and the Nightmare Senche mount.
If you want to visit Tamriel, now's a good time to start.
Once complete, you'll receive the Wyrd Elemental Plume memento and be all set for the coming adventures. The Elder Scrolls Online: Summerset will be available on Xbox One and PlayStation 4 on June 5, 2018, with PC/Mac early access starting on May 21. The Free Play Event period begins today on PC/Mac and PlayStation®4 and tomorrow, March 22 for Xbox One.
Last year, Zenimax Online released Elder Scrolls Online: Morrowind - an expansion to the popular MMO that took players back to the eponymous isle from The Elder Scrolls 3, released in 2002.