1. use the pally as the main, gather mobs up, then mash AE on the mage
This is how I do it.

Round them up, consecrate to get initial aggro in the right place, pop up ice barrier, spam consecrate and arcane explosion together, everything dies

I have consecrate and AE on the same key, so the first consecrate is a click but after that it's just button mashing.

Having said that... I run multiple mages, and I don't think you'll be doing *alot* of tearing up with only one.