Castle Bleck Inner Sanctum is a location in Super Paper Mario. It is the fourth and final area of Castle Bleck and serves as the main setting for Chapter 8-4. It is also the final level in the entire game.
Chapter 8-4: Tippi and Count Bleck
It is just down to Mario and Tippi meaning the area is going to make great use of Mario's Flip ability. Castle Bleck Inner Sanctum is best known for the very large room with different hallways where some have openings to go through. After a lot of traveling, Mario and Tippi eventually reach the room where Count Bleck himself is waiting for them and Mario and Tippi proceed to fight the Count.