The corrupted nether is an addon that completely corrupts the end. The nether has taken hold of it and the withering disease has caused chaos in this realm. The void is now not only a husk of what is too far to reach but now the burning ashes of the ancient holders.

The key to the corrupted nether is not the nethermen, but rather the wither himself. The wither is bound to a withering island. You must find the necessary materials to find a reactor. From here, you need to build a portal in the shape of an end-portal made of basalt. Once done, you can place the reactor in the very center of it. That will make a portal to the withering island. (the dimension may be janky)

He will drop the needed items to get to the corrupted nether. He drops nether pearls that can make the core to gain the nether frames. This portal will lead you to the nether dragon.

The dragon's defeat will mean you have completed the addon. Afterward, you can explore the creatures and plains of the corrupted nether. There will be random treasures and foliations of the dimension to explore. Beware the creatures of the realm.

Withering plains.

Ice-fields. 

In the overworld, you will see the sky world.

The rest of the addon is a mystery.

As well as coming with its own combat system:

Turn these on, and make sure caves and cliffs is on:

creator: https://twitter.com/RocketwayA