[Baalz]

Iron bane + shifters/Einhere = giants going down really fast. Mix in bone fiends to make sure you've got a considerable numeric superiority.

Orb lightning is a better bet than thunderstrike as you can cast it all day long. It'll not only kill them relatively fast, it'll also fatigue them which makes hitting the vans you've got blocking for your casters damn hard to hit. If you're feeling baalzy you can slap some defense boosteres on some vans and carve up the big guys from the front lines via shockwave.

Storm demons...won't take many. Just a dozen or so will carve up stuff faster than you'll believe.