Dark Aura

"Max level 30: -60 MP, Dark Aura's damage increased to 31% damage, when you're around an enemy, do 100% damage each second. Also passively give 30 extra Magic Attack."

From Basilmarket.com's guide on the Big Bang. It also says that Dark Aura gives an 11% boost without the increase from Advanced Dark Aura. Make of that what you will, it's just the guide I've been reading about the Big Bang.

And I've made that guide with the info from this site. The most accurate info can be found here if you look in the correct places.