fire storm

[Illuminated One]

I disagree a bit about the SCs part.
Imo you shouldn't give up armies for SCs. Just like there are army killing tools there are SC killing ones.
Don't build big armies and expect to win though, build forces that are working and expendable (with mage backup of course) and be ready to bring something with completely different attacks to bear when the enemy beats you.
In Late game you can have a gold income of 4000 after upkeep, so you can make 5 800 gp armies, say 2 200 gp mages and 40 10gp troops, combine them at will. They will walk over PD and can pose a threat to SCs even (weapons of sharpness, strength of giants, earth meld for example - though after my experience with low level spells I really wish you could script mages better than merely making 5 suggestions) and as your enemy fills his slots to beat the things he sees he will have to leave some other vulnerabilities open (for example fire resistance or reinvig).
In theory at least, but it depends much on your and your enemies resources, mobility and flexibility (the main problem of armies being that they are not mobile enough).