Isn't the silence a dodgeable ability cast on your location with a travel time from the boss to you?
Just glyph for mobile lightning bolt and never stop kiting. Let your earth ele tank.
It's not as dodgeable as you would think though, especially once he gets into melee range. Stop and cast and it'll hit you. Stop even for half a second, it'll hit you. Don't stop and maybe, just maybe, it'll miss.
Even with body and soul it was hard for me to outrun it.