[Finalgenesis]

If EDM is enabled, there's various AI chaff annihilators there, the most reliable and cheapest seems to be Treant for me, 30 gem summon + 20 gem of gear will see them eat any amount of AI directed chaff with most types of mages.

Another way is an easily accessible (for your nation) linchpin BE spells, eg. darkness for a undead/demon/DV army. There's usually something that goes with your nation/focus well, cold, heat, poison, darkness ...etc, just establish choke points with well supplied armies using said BE linchpin holding them and move out on any direction at your leisure.

small bands of elite Bane wight teams also do great with buff support against most foes, and accessible early on (lvl 3 conj). a bane with a dozen+ or so wights with buff works great (ethereal, luck, quickness ...etc), assuming you have massable D2 access, emphasis on buff.