Yes, the final boss summons ONLY in melee.
http://www.kiya1.de/beyond/act4screens/Finalmeleeend0.jpghere you see the enemies he summoned (was on easy in this screenshot) On tactical he summoned far more.
http://www.kiya1.de/beyond/act4screens/Finalsumm50.jpghere you see one of the summoned, a Warlock. He stripped my char off her requirements to use a weapon, wear protection.
http://www.kiya1.de/beyond/act4screens/Finalsumm2bis20.jpghttp://www.kiya1.de/beyond/act4screens/Finalsumm2bis0.jpgthe Black Bishop trying to place traps
http://www.kiya1.de/beyond/act4screens/finalfireball.jpgsneak+fireball.
Battling techniques by some gamers, click hereMore battling techniques, click hereHm, about the summ. dolls as allies: I didn't try it - other gamers did this. Yes, I consider the Raanaar skeleton suitable - some used them to distract the end boss and gain time. Please, read Grim's posts in the first link.
Kiya