No base to base means no stomps, no impact hits and 1 attack from most of the source, you prive characters of all their attacks except one!
You negate monsters AND chariots AND you got a ward save 5+!
I mean, this is one of the strongest buff magic in the whole game.
I don't see WHY you should charge with temple guards... with movement 4. If you fail the charge you cant cast spells either.
That's spell is too defend infantry.