The Dragonborn has done as told, bringing the priest to cleanse Molag Bal's altar and then killng him... the body of the priest lies dead and
dragonborn kneels at the altar

Molag Bals voice: Insolent Maggot, this slave of plots. Basking in my glory. Ignorant fool, this brave young priest. Sharing in my triumph!

Dragonborn: Master, I hear you. Speak, I listen. Stay by my side. Guide me. Master, my soul was weak; forgive me. Enter at last, my lord

Molag Bals voice: Flattering Mortal, you shall know me. See why in shadow I hide. Look at your face in the Altars blood. I am there inside.

(Dragonborn looks into the blood of the altar before her to see Molag's face)

Dragonborn: lord of Domination, guide and guardian, grant to me your glory. King of Rape, hide no longer. Come to me, strange Prince

Molag Bal: I am your lord of Domination. Come to your lord of Domination

I am lord of domination... Come to your lord of dominationnn