You sure as heck won't until you've beaten the game. Isn't he over level 90? You simply don't get enough EXP for that anywhere if you're not at endgame. Remember, you get less and less EXP depending on your level. I'm level 66 now which is about 6-7 levels below the bosses at this point, and just going one area back means getting like 80 EXP from the enemies that gave thousands of EXP a couple hours ago.
Besides, is beating some random monster really worth ruining all the epic boss fights in the game?
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