The Tower of Dreams was the home and base of operations for the Siblings aka the Brotherhood of the Forgotten, which exists in a pocket dimension allegedly created by Oropo.
It is a titanic magical tower that consists of thirteen floors, each being the domain of each member of the Siblings who are meant to replace their godly parents.
The floors in order are:
1. The Xelor floor, a ruined and dung filled room occupied by the frozen form of Count Harebourg.
2. The Osamodas floor, a swampy temple home to Mishell and her pets.
3. The Iop floor, a sandy column filled arena occupied by Dark Vlad, a dark alternate personality of Master Goultard, to serve as a challenge to the Brotherhood of the Tofu, as Oropo desires Elely to be their Iop Goddess.
4. The Ecaflip Floor, a training room occupied by Ush Galesh
5. The Feca Floor, a giant pinball table/museum occupied by Black Bump
6. The Enutrof Floor, a trap filled labyrinth occupied by Arpagone but really meant for Ruel Stroud.
7. The Sadida Floor, which is a grassy plain broken up into floating islands occupied by Dathura
8. The Cra floor, a forest with an archery range intended for Flopin. According to Echo it was supposed to be floor 11 but Toxxine swapped the floors by unknown means.
9. The Pandawa floor, occupied by Poo but never seen due to the towers destruction.
10. The Sacrier floor, occupied by Kali but never seen due to the towers destruction.
11. The Sram floor, a desolate plane of black rock shrouded by wailing fog that was initially disguised as the Cra floor.
12. The Enripsa floor, Echo's spacious bed/dinning room that is difficult to enter and exit on foot due to slippery walls and an apparent lack of doors.
The order of the floors was shown at the end of season 3 episode 3 via an image conjured by Oropo, though, curiously, in the image the Sram floor is depicted as floor 11 and the Cra floor as floor 8. Foreshadowing Toxxine's trap.