Unfortunately, the plan went rather drastically sideways, and Crowley died at his own hand mere minutes before Lucifer managed to stab Cas with an angel blade from behind.
Misha Collins wasn’t kidding when he said that the Season 12 finale would mix things up for Season 13.
The Winchesters did successfully trap Lucifer away, but the success came at a high cost.
Less hilarious is the fact that Lucifer seems to have actually succeeded in killing Castiel for keeps, seven seasons after he was first thwarted by God.