There's a particular fic that I'm ripping my hair out to find. It was set post season 5 and AU after that, where Castiel (as sheriff of heaven) takes Dean up to heaven in order to try rescue Sam from Hell. 



The fic has Dean/Cas, and Crowley and Aziraphale from GO are also enlisted to help (Crowley is the same as SPN!Crowley here, and Cas raises him so he goes by the name Caphriel). The rescuing process involves uprooting the Tree in the Garden so that it reaches into Hell for Sam to (in theory) climb out by, although they end up rescuing Adam because it's revealed that Sam is already out of the cage. I remember Joshua also being a character in this fic, supporting Cas. Cas loses his massive amount of power at the end from the rescue attempt.



Does anyone recognise this? I've checked a couple of crossover listings but haven't managed to find it at all.

ETA: Found to be Strike Me Down and I'll Become More Powerful Than You Can Possibly Imagine by nebularific!