I use a staff that causes 10 seconds of paralysis. I just paralyze the enemy and then flame the hell out of them. Rinse, repeat.
I found that staff. It's worth a fortune. Trying to decide whether to use it, disenchant it, or sell it.
Edit: It sounds like a perfect weapon for a Mage. Do you know where you got it? Would love to get it when I create a mage character.