I understand this is not really an exploit, but as far as I'm aware, this is not a very spread fact, and might not be intended by Blizzard.
If you use your passive skill "Arcane Dynamo", and get five stacks, and use Hydra or Archon form with "Disintegration Wave" (Right-click) with 75% increased damage for the cast's complete duration.
Can be good for sick pulls, or treasure goblins etc. With 46k damage, my disintegration wave is hitting about 160k about twice a second.