In your opinion, what "game element" (*) most closely approaches the mythical state of being "overpowered"?

Clearly it doesn't quite reach that state or it would have been toned down already. I'm interested in what you think might be "on the cusp" so to speak. Should make for interesting discussion.

"game element" = skill, spell, song, commune, power, item, race, class, weapon spec, form, cabal, or any combination thereof.

Feel free to define "overpowered" however you wish, but do include your definition. Mine is: "something that's fairly likely to kill me even when I'm trying very hard not to die."

I'll throw out my candidates once a few folks respond. Or not, if there's no interest.