Lucifer: Asmodeus was my weakest creation.
Castiel: Doesn’t seem that weak to me.
Lucifer: Yeah, yeah, that… that whole shape-shifty thing he does? I-I didn’t give him that. But so what? The old dog’s learned some new tricks. Eventually, he’s gonna mess up. Then he’s mine. Okay?
Castiel: Excuses aside, you’re saying that you’re too weak to overcome even your weakest creation.
Lucifer: Shut up.
From Supernatural – Season 13 Episode 12: ‘Various & Sundry Villans’ (13×12)