I am using them too, but not at the expense of my own hero - I just always try to leave some surplus runes around and wait until 2 more levels to get a new skill, until that time they can kick ass.
I have found a new spell that so far I think has not been reported:
Totem of Adrenaline (Chaos): In place of a Fallen troop, raises a totem which on each move (round?) increases the Adrenaline level of Orcish allies, while at the same time decreasing the defense of those who stand against the orcs. Has no effect on creatures immune to mind spells.