If you ask me...I think that it will be a "nature" spell, what will raise the def value of the units. There was a game with the spell "barkskin" and it was a defensive spell, I think it was in NWN.
"Training is principally an act of faith. The athlete must believe in its efficacy: he must believe that through training he will become fitter and stronger, that by constant repetition of the same movements he will become more skillful."