ππππ ππ πππππππ πππ π ππππππ ππππ. πππ ππππ πππππ π πππ πππππππ πππ ππππ
City of Dalaran, the new 28 to 33 dungeon, has a hidden boss called Lyn the Ignored down in the sewers, and the thing that summons him comes from a different dungeon.
After you kill Arugal in Shadowfang Keep there's a book on his table now that gives you a Black Tome. You carry it over to the keep in Ambermill, use it next to the Ambermill Leyline Focus, and it turns into the Tome of Dalaran. Then in City of Dalaran you kill the first boss, Atrexis the Grave Knight, and instead of going right toward the surface you keep going straight through the sewer tunnel to a purple rune on the ground. That room looked like a dead end until the dungeon opened. Use the tome there and Lyn shows up, with a little entrance that nods at Ragnaros: too soon, you have awakened him too soon.
The tome isn't used up and it only has a 3 minute cooldown, so a wipe on him is not a trip back to Shadowfang Keep.
Kind of love that Blizzard is hiding stuff like this in the new dungeons. Makes me wonder what else is sitting behind a dead end nobody has clicked on yet.