As the Lord of Destruction, even though his body was destroyed and his soul captured by Roy, Baal was fearless.
In Roy's hand, his soul distorted and transformed into Baal's ugly face. He roared at Roy, "Osiris! You will pay the price for your betrayal! The souls of demon kings are immortal. Even if you can destroy the Hellforge, at worst, we will be expelled from this world and return to the Abyss. At that time, we will find you, kill you with our own hands, imprison your soul, and torture you forever!"
Roy ignored his clamor. He took out Kanai's Cube and stuffed Baal's soul into it. "Go accompany your brother!"
At this moment, the souls of five demon kings had been collected in Kanai's Cube. They were Baal, Andariel, Duriel, Belial, and Azmodan. Belial and Azmodan had died in Lilith's hands, and she couldn't destroy their souls, so she brought them to Roy.