@Mortein: All I'm saying is that if Buu couldn't regenerate do you think he would have survived his own blast. There is a Difference between Regeneration and straight up durability.
@hitsusatsu11: A half dead Frieza survived however, then there s Kid Buu's blast on the earth still no where near the condition Freiza was in yet they died as well. So at best the DBZ characters a planet busting attack is all they can really take, anything more would kill them instantly.
@hitsusatsu11: Dying in Cells Attack sort flush that down the toilet though. Cell said when he blows up the planet will go with him. Since goku has never tanked a Planet busting blast before that is the only thing you really have to go by.