User blog comment:KillRoy231/The death in Hell's Angel/@comment-3423279-20160404101607

Probably Castiel only, as if they kill Lucifer it is basically impossible to defeat Amara with the only pieces on the board strong enough to do so are either dead, missing, or the writers refuse to introduce them.

We can't have this season done in one episode can we?

As for that whole The Empty is a place that one cannot be resurrected from, well, a simple Reaper says that.

God, Death, and Amara are so powerful that a Reaper's definition of "impossible" is almost certainly easier to do than dusting off a coat. The three of them are as close to omnipotent and omniscient as there is in this show, and they are basically unbeatable.

Unless Death has a derp moment and gives a human the only weapon in existence that can kill him instead of.. I don't know... a gun? Maybe Amara will give Sam the "Darkness Blade" or something like that instead of Dean who is useless against this villain, and he will casually walk across an entire football field in plain view of Amara while she stands there and waits to be defeated.

As for Rowena, well, she only died as a human while in Hell. Her return is entirely unsurprising to me because of this, and I don't know why it is to others.