I'd speculate that halving is probably a suicidal build or painfully slow one for mages because you simply don't have enough runes to get enough happy rage control.
You sort of need enough rage for decent "jealousy" skills and there aren't enough might runes for you to max your magic tree (which is far more efficient for you anyway thanks to the Archmage skill).
At least, this is from a perspective of a non-targetable core unit+ nuke spells and disposable summons approach.
More troops is more liability especially for the lackluster leadership mage.
[edit] oh wow, noticed impy still has so many might runes. I wonder where all of mine went? I'm guessing still in the mage tree as I have like 90 spirit runes which I don't plan on using.
