Audio book i cant remember the name of.

Guys, i recentlv remeberd an audio book series i heard about 10 years back and cant remember the name and hoped you could help me. The few thinas i can remember is that its a fantasy story and that the protaqonist is a prince, a few snipits i also remember are that there is a guy who summons demons to over throw the crown and that there is a book bound in whats probaply baby skin. Also the protagonist is transportet to hell, theres always only a prince of hell and they have to eat theur predecessor. Theres also a purple palace that was sun bleached, some wizard guy that summoned a demon by making a pentagramm from goat skin and i belive some isekai'd guy.

Thank you in advance, and im sorry for any spellimg mistakes.