My muken has almost 1,7M att and does no dmg in void.
http://bleachjf.gametrees.com/fightreport/?rid=57987527517880960&aid=68&t=1&lang=en_US
He survives 20 rounds and still hits for no dmg.
Even kokuto with 1M kido att deals 5 dmg.Muken does nothing.