I have level 30 character monk, black/white mage and fighter, and I managed to beat the dragon and cerebus. The trick is to haste/temper them as quickly as possible while keeping nullshocked/blazed/whatever. My monk was doing 16 hits with about 1500-2000 hp by the time i beat the cerebus, and my fighter was doing almost 1000 when I beat the dragon. The other two are too hard, because they quake me to death too quick and I don't know what to do.