Build Description
I'm not sure exactly how strong you must be to beat with this build, but it worked for me as soon as I finished the main campain (up to summit) on Hard.
BTW, buff beams on minions can be 5DU instead of 6DU, then you can implement more reflects. Note that most of the projectile being thrown at your minions will come from the stairs though.
I never tried this build on multiplayer, only on solo and with only one hero summoned.