Build a portal made of Diamond-Studded Deepslate, light it up with a Diamond and Deepslate and just hop in. Explore caves made of lava and fight dangerous mobs like the Sculkling and the Bigling. There ist a boss named The Weirden, and it drops a Heart of the Sculk. You can craft OP gear from it, like the Sculk Gun or Sculk Multitool. Then you must farm some rare materials to craft Cursed Sculkstone, make a portal out of it and enter Blavodia.
Please check out HellementalSnoob too.

The mod added:
Dimensions:
-Sculk Dimension (I'm still trying to find a better name for it)
-Blavodia
Biomes:
-Sculk Mountains
-Sculk Oceans
-Sculked Forest
-Darkwood Deepforest
-Darkwood Jungle
-Darkwood Plains
-Purplewood Mountains
-Cursed Dragon Valley
-Bloodwood Forest
Blocks:
-Sculk Block
-Sculk Wood:
-Logs
-Planks
-Wood
-Stairs
-Slabs
-Pressure Plates
-Buttons
-Doors
-Trapdoors
-Fences
-Fence Gates
-Sculk Stone
-Sculk Stone Bricks:
-Bricks
-Cracked Bricks
-Carved Bricks
-Stairs
-Slabs
-Smooth Sculk Stone
-Sculk Cobblestone
-Deep Sculk Stone
-Smooth Deep Sculk Stone
-Deep Sculk Cobblestone
-Cursed Sculk Stone
-Darkwood:
-Logs
-Wood
-Planks
-Stairs
-Slabs
-Fences
-Fence Gates
-Pressure Plates
-Buttons
-Thallainium Ore
-Thallainium Block
-Feinerite Block
-Feinerite Debris
-Purplewood:
-Log
-Wood
-Planks
-Stairs
-Slabs
-Fence
-Pressure Plate
-Fence Gate
-Button
-Leaves:
-Sculk Leaves
-Darkwood Leaves
-Purplewood Leaves
-Bloodwood Leaves
-Cursed TNT
-Grass:
-Darkwood
-Sculk
-Purplewood
-Bloodwood
-Bloodwood:
-Log
-Wood
-Planks
-Stairs
-Slabs
-Fence
-Pressure Plate
-Fence Gate
-Button
-Diamond-Studded Deepslate

This mod is made with the mod creating tool MCreator.
Blavodia is still in developement.
It's recommended to use JEI.
If you play the mod in English, please use "English (USA)", otherwise you could have not the right item names.
This mod is currently not developed on, but I will return to it.

Soon the 1.18 version will be there (5.0)
I'm still working on 5.0, but can't fix some problems:
-In existing worlds you can't enter the Sculk Dimension anymore
-You can't create new worlds (he says: Errors in currently selected datapacks prevented th world from loading. You could try load it only with the vanilla datapack (Safe Mode) or go back to title screen and fix it manually)
These problems are solved now, and Sculk Dimension 5.0 (for 1.19, not for 1.18) will be here before 2023