User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-26992577-20150923233420/@comment-24834479-20150923235248

First of all, the title of King of Hell doesn't grant you any abilities. If Lucifer had the Mark of Cain, tapped into a word of God, and absorbed the billions of souls within Hell, I think that he could beat Death. My reasoning is this: Castiel, a seraph, with millions of souls became so powerful, he gained the title of God, and was almost cocky enough to fight Death. He wouldn't have been able to beat him at that power level, but still, he could have held his own for a while. If Lucifer, an archangel, had absorbed billions of souls, tapped into the true energy of God, and into the power of the Darkness, then yes, he could beat Death. Also, with the mark on his arm, he couldn't die, so he has beaten Death on that way as well.