[Cohen]

Far better, if you can afford it, soul slaying with spell focus.
If you can get too some comm slaves to raise the astral power is better too.

But remember these are all lucky check on dices, so on both soul slay or ethreal xbow aren't sure.

Undead SCs are the easiest to take out with Dust to Dust or Whiter Bones or Solar Rays.
Drain Life works with all SCs.

Petrify hold them or kill them directly.

Well those are cheap for sure, but some need high magir research and a good spellcaster.

Instead of living statues that are spent gems, I advice common troops. If the problem is the renewing of life points by killing living troops, soul slay, ethereal xbow ignore hit points.
If you go for direct damage, having a barrier of SCs Fodder could cripple your battleplan.