[Tallenn]

I was going to bring this up, too.

From everything I remember on live is that when mobs who run drop below 20% health, they start running (again, unless there is some other circumstance, like they have friends nearby, or you are also low health). On P99, it seems that when they run is some random number between maybe 0% and 10%. It's not consistent, even on the same type mobs that are the same level from one kill to the next.

Also, if a mob is green to you and is a runner, it will often run at much higher %- at least if it is really green, like 10 or more levels below you.