True Authority.

He also can't create powerful avatars that can distance themselves from him anymore since he sacrificed all his crowns. He is all the firepower he has at his disposal. 

He is not a demon king either, and he has lost both the recognition of the abyss and the benefits of one. But he is not useless. He is a Demonic Spark, an actual, albeit not orthodox, divine spark. So even though he has lost the support of the abyss, he feels it is a worthy exchange for the ability to create Authority with cosmic energy. 

Legion has always wanted to gain the ability to create Authority and they were right about its abilities. Unfortunately, they didn't break any tenets of the void universe now that they have achieved it. What's worse is that he can't create the Authority of the Void Universe.