Anachronos at the Caverns of Time in Tanaris wants the Staff Head of Atiesh and the Base of Atiesh.
You question why you are still alive. After all, you have in your possession an item of great evil. The answer is not clear, <name>. I only do as I must.
Kel'Thuzad sits atop his throne in Naxxramas, plotting... He seeks that which you hold and holds that which you seek.
As for the base of the staff; the dwarf, Brann Bronzebeard, held it when he entered Ahn'Qiraj. He has left Ahn'Qiraj but the base of Atiesh remains.
Should you succeed in recovering the pieces, return them to me.