New Dimension: Badmist

After killing the Ender Dragon, you should receive a book that hints that killing the Ender Dragon was just the beginning. That book should tell you how to make Badmist stone. Making Badmist stone should be very hard, as in having to shove magma blocks into a block of iron on every side at precisely the same time. Even then, there is a chance that the block will just explode, but there is also a chance that it will make 1 block of Badmist stone, which can then be mined with a pickaxe. Arranging Badmist blocks in a particular formation, along with building an altar, which would require items from the outer islands of The End. Badmist would be a large island in a never ending sea, and would have outer islands accessible by boat. The terrain would be a thick foggy forest, made out of eerie black trees, with some lakes. The weather would always be overcast. The main mob would be Shadows, which are creatures that vanish when you get too close. In the center of the island is Shadows Keep, which houses The Whisper. The Whisper would be a naturally occurring boss mob, like the Ender Dragon. It is always shrouded by black smoke, and you can never see it's body, only yellow eyes at the center of the smoke. The smoke never clears enough to see it's entire body. The goal is not to kill the Whisper, but to retrieve a chest, located at the center of Shadow's keep. The Whisper will be almost immortal. Technically, it could die, but for all practical practical purposes, it would be immortal.