The Green Lions from Manifest Vitriol are very interesting.
Their breath is acid, so cannot be resisted, and hits multiple targets for rather devastating damage.
I haven't tried them against a real opponent yet (not many mages come with F+W), but when I did some test summons, they absolutely annihilated normal chaff.
For 2 gems apiece they seem to be quite lovely, if you can get proper blockers in front of them, and their spit doesn't hit your own troops.
Maybe use Wind Guide, if you have Air mages.
