Caverns of Time: Opening the Dark Portal Jan 9 2011
This is the second instance in the Caverns of Time. You must travel back in time to stop the Infinite Dragonflight from preventing the opening of the dark portal by Medivh. The Caverns of Time are located in the eastern part of Tanaris, but there is also a portal in Dalaran that will take you there.
This is a level 68-70 dungeon. You must defeat 18 waves of enemies, each spawning at 1 of 5 random locations in the dungeon. Waves 6, 12, and 18 are the three bosses Chrono Lord Deja, Temporus, and Aeonus. In order to enter the instance you must complete The Escape From Durnhold Keep instance first.