Only uber Diablo has Armageddon, and yeah as DC said it's worthless for range.
That being said Diablo's longest range attacks would be fire ring > firestorm > lightning hose. But the fire ring and firestorm travel along the ground so they aren't useful against guys at different vertical heights. Going by diablo "yards" the fire ring's range is pretty large though. Like a hundred yards at least. Firestorm is probably like 40 yards and lightning hose probably like 20-30.
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No problem!
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