: Sam and Dean are visited by an old friend— Eileen Leahy , a hunter who was previously killed by a hellhound. Key Plot Lines :

: Sam uses a spell left behind by Rowena to bring Eileen back to life. This arc explores Sam's growing proficiency with witchcraft and his lingering guilt over Rowena's death.

: Season 15 is the final chapter of the Winchester brothers' journey, consisting of 20 episodes.