Umbrals....

[ComTrav]

I had better luck with Sirrushes (in SP) as C'tis, because they're poison immune.

With the high MR and Army of Lead, you'd better have penetration items for Soul Slay to work.

What era is this? Arco/Agartha are both in every era. I'm guessing MA because you said you had so many Astral mages.

[Saxon]

It is MA

[NTJedi]

If he's using 'Army of Gold' then it should be making those Umbrals vunerable to lightning. Bring some lightning immune troops / thugs and cast 'Wraithful Skies' . Also combine it with the death spell 'Wither Bones' using penetration items.

The Sirrushs, cast 'gift of flight' and have them setup for hold and attack archers.... which will hopefully keep them away from those Umbrals.