Raistlin, it all depends on what you're dualing from and to. If you are dualing from kensai to mage you would do it at Level 9 because you will max out your mage levels dualing at that level. It's basically a formula:
Old XP + New XP = 2.95million
Obviously this will differ from class to class.
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Memnoch - Custodian of the Holy Flame 