The Defias prison where nobles were held for ransom, now under naga attack.
Blizzard showed it at BlizzCon. It sits on the island off Dustwallow Marsh that players could see but never visit.

On Alcaz Island, off the coast of Dustwallow Marsh.
Zone: Alcaz Island, Dustwallow Marsh
This dungeon has no Classic version, so there are no old guides for it. What's here comes from the beta and the first weeks of Forever. Blizzard is still tuning it, so check your tooltips.
Blizzard showed this dungeon at BlizzCon, but its bosses, loot and quests haven't been found yet. This page will get full boss guides as soon as the fights are known.
No bosses have been named publicly yet. We'll fill this page in as soon as the dungeon opens and the fights are known.

Boss fights go smoother when you're not thinking about your rotation. Build one on the portal's Rotations page and Compass+ shows the next button to press, so you can watch the floor instead.