Low health boss that hits for tankable damage? Only 2 adds at a time? This boss is gonna be easy!!

Or is it?

At first I thought it was gonna be one of the easier bosses. But after the downing the initial wave of adds and healing myself back up, my mana bar is already 60 - 70% depleted. So i guess the only tip here is to get mana back as much as possible with SW:D (or dispersion)