The final part of a high level dungeon I created, loosely base don the same tower from Final Fantasy 1. The tower was created by the gods to test & forge people into heroes, being granted legendary weapons at the top. As such, each floor is basically it's own pocket dimension with it's own rules & types of enemies, and there is often powerful magic that can hinder or restrict the players. Each tier is meant to take one adventuring day, with 2 short rests and a long rest.

Tier 3 covers floors 11-14 as all the peak. Here are the notes, rules, & themes intend for each floor.

F11: rest, no map for it, not needed. It's a large room that magically provides whatever they need for downtime, meant to take a long rest here.
F12: Arcane, standard dungeon but filled with magical traps & creatures, as well as a few items.
F13: Lovecraftian, the most unique floor, takes place on an alien planet, the rooms & walkways are basically safe places to walk. The rest of the floor is covered in 10ft tall swaying tendrils. You can fly, but lovecraftian creatures like the color out of space attack if you do. The tendrils try to pull you in if you walk through them. This floor was meant to slowly affect their mind the longer they were in it. Filled with lovecraftian & space creatures.
F14: Cave, standard dungeon cave filled with some earth creatures & dragons.
Peak: The final floor, has a short rest area and then the peak of the castle sitting atop a layer of clouds. Here is where they are meant to fight the final boss & prove themselves heroes. In my campaign, they had a multi-boss fight with a dark knight that rode atop a metal dragon while Bahamut, the King of Dragons, as well as God, watched and presented them their legendary weapons afterwards.