Talk to Castiel. He and Loki and the kid are your best shots. This won't be about strength. This will be get in, get Crowley, get out. And after that, even if you do pull it off, it starts to get worse. He won't let this lie. He'll come at us hard, harder than he ever has.
So maybe I'm not being constructive and maybe I am willing to leave Crowley where he is. Because I know what will follow if you do this. And Crowley knows too.