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)