Changes

The [[Witch Mother]] makes it clear that the resurrection [[spell]] can only be used once, telling Sam that once [[Death]] sees a loop hole, "she closes it." How the Witch Mother was aware that Death was female is not known, as [[Rowena]] was surprised to learn this fact in [[13.19 Funeralia]]. Its possible this has become more common knowledge since then as the Winchesters themselves didn't find out until months later.

Sam states that Rowena was maybe the most powerful witch to ever live. In return, Sam is called "Rowena's protégé" by Dean and it is implied that Rowena specifically left her magical stash for Sam to inherit and use. Indeed, Sam displays a growing magical ability, being able to resurrect Eileen and kill the [[Witch Mother]] using a spell he learned from Rowena. He was also able to finish the creation of the resurrection spell which that Rowena had never completed.