User blog comment:Victory awaits/The actual outcome of Apocalypse?/@comment-87.116.253.21-20161002110418/@comment-87.116.253.21-20161002210501

That means that nothing could KILL LUCIFER because Death was his slave .When someone bound  Death  nothing can kill him. Even Death said in s05e21 that only Sam can stop Lucifer so maybe Death knew that Lucifer would won the battle