"I've learned a great many things, Zalem... Some of them not learned willingly. Necromancy is but one of them. There are many things in motion and I'm here to stop the one about to destroy everything within two day's journey."
He continued to walk, angling his path so he would pass around Zalem. 
"I also remember you as one of my students, although 'old friend' wasn't altogether inaccurate. I may have been fond of you back then but if you continue to get in my way I will have no choice but to treat you as one of the prophesied minions of the dark. You know well what I do to my enemies in capacity of wizard of the first order."