I have a plan to fix the swarming problems. Create a new character stat (we all crave more stats right?) for mental fortitude that will determine how many aggressive mobs a given character can handle. Kind of in the same way your mercenary cuts out after you pull too many mobs. What if as you pull too many mobs your character becomes less responsive? Maybe certain skill types can only be active if you have a certain amount of mental fortitude renaming. Perhaps your character has a mental break the first time they kill one of their own!
That would mean your character gets less responsive if you simply have a bad pull, or run through a zone and pass a see invis. Pulling and splitting would be unfairly penalized. It would also create a system players could game to continue swarming or whatever form of mass killing their class uses.
Plan A: Create a totally new stat, retroactively add gear and/or AA support for it, change the basic aggro/assist code of the game, deal with issues caused by these enormous changes and their effects on 15 years of existing content that was designed with existing aggro rules in mind. Plan B: Simply kill all forms of swarming without changing any game mechanics. What a tough choice!
