My strategy on Creator (sorry for my engrish): I made a wizard, bought best equipments, used all points on INT and willpower and got these stats: 5000 hp, almost 3000 mp (with 250 willpower), 330 INT, all at level 60. You don't need to get that high I guess.
I noticed DARK (400 mana) was doing around 2k-3k damage, HOLY (200 mana) was doing around 1500 damage and FIRE (20 mana) was doing 1000 damage, so I used fire a lot of times (creator has 25k hp) and healed with CURA (150 mana, cures around 5k hp) once in a while, because curaga is too expensive and kinda useless (cures around 10k hp, such a waste). I ended having a lot of extra mana so I guess you can beat it earlier, just be careful on the timing of the healing, I always did when having around 1000hp, hope this helps.
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