Caelum is actually very well balanced. Their troops are quite weak, and the beefier units are resource intensive. The only real draw for Caelum is it's mages, which is thematically appropriate, being a society ruled by it's mages. If the Seraph's were nerfed, Caelum would turn into a weak nation, and thus, unbalanced. Luckily, the devs agree.
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My plans are always practical! It's the laws of physics that get in the way of my success!
I found out what zombies are weak against.
Oh?
Point blank annihilation.