Lucifer also knew that the only thing this man cared about was getting out of this prison. That meant that Lucifer was important for this cause for him.
Licorice had already destroyed so many people dear to him. They were dead because of him. And Milena was also dead because of this Lucifer and him. He couldn't care any less for these two people. If hurting Lucifer could stop Licorice and make him regret messing with him, what could be better?
Lucifer clenched his fist, destroying the heart of the other Lucifer, crushing it to nothing.
Even though he knew that Lucifer could come back to life with healing through, he still chose to do this to mess with Licorice. Moreover, this could keep Lucifer out of this battle for a little while.