Does SCS make mages too hard to kill?

I find spells such as breach, ruby ray, warding whip and pierce magic to be inconsistent at best, and it really made me rethink the order in who to attack first and when and how. Most of the lower level mages are easily dealt with the standard ways involving lots of melee and maybe a breach. But then there are the medium difficulty and higher who take a very long time to make vulnerable, and I don't really know any other way of dealing with it than distracting them with animate dead while I handle the warriors and priests by stabbing them to death or dominating them. I try starting fights by hitting the mage with poison from darts or arrows or insects and sometimes they work, but it changes nothing. I distract with animate dead so I can kill them last and the mages fighters and priests first.