Every so often one of my mage slaves would pull agro. It got so bad that at level 40 I had to solo him for an hour to get caught up in xp to the others because he was always the first to die.

I fixed this by makeing sure each toon had the exact same gear. I was useing an excell spreadsheet to see when items dropped what slave it went to so I could maximise. One toon would end up with a few less resists and a few more crits and just be the target of the mobs desire.