Introduction:

JJThunder King of the Nether is a split-up version of JJThunder King of the Hills, where it only terraforms the nether and not the overworld.

What it does?

Increases height of nether from 128 to 640
Increases depth of nether from 0 to -128
Lava oceans are at y=-114
Removes default world generation of the nether and instead replaced by custom world generation.
Nether is split into underland and overland.
Underlands have cave-like generation ranges from -128 to 350
Overlands have mountain-like generation ranging from 400 to 640 (no more flat bedrock roof!)
Smooth transition is applied between 350 and 400 and is mainly covered with netherrack
Adds lava acquifers to underlands, so you wont have to wonder around the bottom to admire lava oceans
Nether portal teleports to near the bottom of the world (At negative height), so you would have to climb up a journey to reach the overlands!

Notes:

Allocate at least 4GB RAM to the game.
Not compatible with Incedium and other nether world generation data packs.
Compatible with biome mods like better nether.
This mod is incomplete by its own, where it only terraforms nether without adding new biomes, thus it is meant to use at least 1 biome mod.
Do not use this mod in existing worlds as it would corrupt these worlds.

Data pack Version:

JJThunder King of the Nether without mods: