Make sure you are the proper level to go on to Zafaria. You need to be a level 55 wizard to go there. Complete some side quests to get more experience to level up so you can head on over. If you are level 55 or above, then I would check out Celestia to make sure you have truly finished all of Celestia, and if so, then go see Merle Ambrose and he should have the quest for you.
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