Let's begin with the New Stone Types!

Paraibya/Burmastone and Berly Shale Stone
All Spawn around the Nether but Paraibya only in the Warped Forest
 

Next up we got Wood Types!

Death Cap

Death Cap spawns only in a Biome called the "Death Cap", it is a green Stem block!

Chaga 

Chaga Stems are only found in the Crimson Forest and spawn pretty commonly there. it is Black and Orange

Psilocybe

Psilocybe Stems only spawn in Warped forests and are pretty rare. It is purple and red.

Next Up Mobs!

Blazes when spawning in Crimson or Warped Forests or Soul Sand Valleys now have a different skin!

And there now are Baby Ghasts! They do not attack the Player

And there is a new Creeper spawning!

Chaga, Crimson and Warped Mooshroom 

spawn around the nether! they work like normal mooshrooms but just for their own Fungi type. You can even milk their stew!

Now we have the Ores!

Mercury and Gallium 

They spawn commonly in the Nether and need a Bucket to be picked up!

Mercury and be made into a Potion that removes Wither, Poison and Fatal Poison for 2 Minutes! But if taken more then 5 Times it will give the Player a 2 Minute Wither effect

And Gallium can be used to Duplicate Metals and To Fix Anvils!

And with Mercury and Gallium you can make a new TnT!
 

Platinum 

is pretty much the same as iron, just a bit stronger and for the Nether!

Bloodstone Gems

Bloodstone Gems are the same as diamond but for the Nether!
But the Armor+ Tools have an Lifesteal effect 😀
 

Essences And Souls also have been added!

They can be used for scrolls! And the new Boss
 

You can now make and find new Warts!

They can be crafted aswell and they make new decoration blocks and akward potions!

Soul Pumpkins

They spawn in Soul sand Valleys and they grow from small to Big on any block

There also exists the SOULSTONE now!

And there are three new structures!

The Soul Tower! Spawns rarely in Soul sand Valleys
 

The Warped Nether Ship spawns everywhere not very common
 

Obsidian Spikes that spawn in Lava Lakes and they spawn Blazes!

And Finally..
The Boss of the addon:

The Withering BLAZE.

You summon it by placing a Withering soul Pumpkin on two Bloodstone Blocks.
And then... wait, I will let you figure the fight out 🙂

Here a tutorial Video!

And that is about it!
Yes This Addon isn't suppose to change the entire Nether, therefore it is just a pretty small addon!
I hope you enjoyed it tho!

https://youtube.com/watch?v=YgJyxQrl7Jc&si=EnSIkaIECMiOmarE