Random Encounter. Who wins and why.
Well, the Djinn is leagues above a bunch of villains (he can easily survive blasts from characters like Galactus) whomever, the only work trough wishes. If someone wishes to Voldemort not exist anymore, he does with little trouble at all.
If the Djinn doesn't have the Messiah of Destruction (the guy who summoned him) the battle will end for eternity.