I did a quick search, but I don't think I saw this question answered:
Do the three targets for Tempest's Chain Lightning need to be different targets? Can I target a Villain three times with the card, or possibly target Villain-Minion-Villain?
We played it as if the targets must be different, because it seemed a little too powerful, otherwise, but I figured I'd ask for the real ruling.
Long answer that isn't a tired joke: Chain lightning refers to a second target and a third target. These can't be the same target because then they'd be the first target rather than the second (or third). This wording also applies to Bunker's Grenade Launcher.
A good example of the contrary (targets can be the SAME) can be found in Scherzo of Frost and Flame, which just says "target", not another target, or a second target :)