The way I handled the mobs running at low health...

70 pally parked spamming holy shield/consecration.
40-42 priest healing him.

40-42 Pally/Mage/Mage would run around as they fled spamming arcane explosion.... normally one or two taps of AE would down them, and I could do circles outside the main pack to not get hit with the fireshields.

As for the casters, I would round them up using counterspell.

Ultimately I see this being a VERY valid way to powerlevel characters when Team Doublemint hits 70th... bring in the pally + 2x mage and 2x level toons and clear it faster than you can blink.