The problem with soul of rebirth is getting to the emperor, I beat him and everyone had less than 2,000 hps but the hardest time was getting to him the emperor himself is a pushover. The best thing to do is give Ricard Wyvern/Dragoon Lance (Cant remember the name) + defender and some other stuff to make his evasion 99% (This is pretty easy) and cast berserk and haste on him in about 3 turns for Ricard you will have the emperor killed as he only has 15,000 Hps Dont overthink this battle its really simple just cast Berserk and Haste on Ricard and then have every else use cure or damaging magic (whichever they know) while Ricard attacks.