If enemy 'blood' mages would actually use blood magic spells the game would be much harder. As it is now, the tag above their heads should be changed to "Amateur Poser".
If enemy mages would use Mana clash, the game would be nightmare for PC mages. The only time my mage fell in her playthrough was when by chance that special mage in the Temple of the urn used Mana clash on her = instant 202 damage & knock-out. *giggle*
Usually when Emissaries use Curse of Mortality or Crushing Prison, it's knock-out time for one of the party members too. But they hardly ever do.
In Baldur's Gate at least enemy mages didn't hold back... but usually cast 500 spells instantly as soon as they spotted the party.