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.$B$B*WARNING!* You can only select one alchemy specialization.