The denizens of Kalimdor would be relieved to know of this victory. Take Ossirian's head and present it to Commander Mar'alith of Cenarion Hold.
Ah, <name>, you have returned! And in one piece, I might add. What news do you bring from Ahn'Qiraj?
I offer you my highest commendation and your choice of an item of power, <name>. You have done the people of Kalimdor a great service.