This quest is not available in game.
Go to the Black Morass in the Caverns of Time and obtain 10 Essences of Infinity from Rift Lords and Rift Keepers. Bring these along with 5 Elixirs of Major Defense, 5 Elixirs of Mastery and 5 Elixirs of Major Agility to Lorokeem in Shattrath's Lower City.
*WARNING!* You can only select one alchemy specialization.
- Elixir of Major Agility × 5
- Elixir of Major Defense × 5
- Elixir of Mastery × 5
- Essence of Infinity × 10
I've devoted my life to perfecting my elixirs. Despite my success, I haven't been able to create an elixir of eternal life.
I think I know the reagent I'm missing. I've heard of a place called the Caverns of Time in Azeroth where intruders known as rift lords and rift keepers phase in and out of the timeline.
This intrusive time-shifting creates tears in time itself, twisting it infinitely into crystallized essences. Bring these to me along with samples of your work and I'll teach you all I know.