to beat the girl and giant you need to focus your attack on the big guy because if the girl is killed hell become berserk (all stat boost and able to 1hit u) u also have to heal now and then to make sure you dont die along the way,
anyway once the big guy is dead the girl is easy pickings(note when you reduce the giants hp to about 1/2 shell only use 800 hp heals and have infinite mana, you just have to do more damage faster than she can heal)