I've been fooling around with MC quite a bit lately and I noticed that the aggro of a controlled mob is not transferred to me after the mob dies.
Meaning that priests could conceivably solo-clear anything where they can use MC, albeit slowly. Because you can MC one mob of a pack, then when it does, the rest of the pack ignore you. MC another one, get it killed, and so on. Either nuke the last mob of a pack or place yourself so that you can MC it and use it to fight the next pack.
I don't know if this is a bug or the way MC worked back in the day.