Well if you have all those researched. I'm sure having Astral Fires is no problem. So he'll just cast that, and your poor undead all die.

Boo-hoo. ;P

Or maybe he has a JMC on a guy with an Eye of Precision. They are fairly accurate even across the entire map.

Or maybe, all they do is cast Paralyze with someone with 4+ in Astral, and paralyze you even with 24 MR.