VIBRANT VISUALS AREN'T COMPATIBLE AND NO EXPERIMENTS NEEDED

Note the new nether biome may have generation problems, this is due to a bug with minecraft, please do all addon developers a favor and vote on the bug to get Mojangs attention on it! this bug is the reason why i and other developers havent made any new nether biome addons
Custom Nether Biomes bug report

Tempered in Flame copletely redoes the generation for all nether biomes and changes Nether Fortresses and Piglin Bastions to have a completely new look depending on the biomes

Sidenote for bastions, all bastions are changed, not just the one shown in the images, im only showing one off of the variants off.

NEW BIOMES:

Irradiated Wastes: The Irradiated Wastes is a brand new nether biome that is themed off of nuclear radiation, it has a ton of dangerous blocks and mobs inside it, with a handful of new structures, as well as its own boss

BIOME OVERHAULS:

Warped Forest:

Biome rework: The Warped forest gains a ton of new plants, nether wart can also generate on the roof part of the biome and theres a ton more twisting vines, as well as new variants of trees, the trees can also stack on top of each other, Endermites now spawn here

Warped Nether Fortress:

Warped Piglin Bastion:

Crimson Forest:

Biome Rework: Crimson Forest essentially got the same treatment as the Warped Forest, except instead of a ton of twisting vines, it has a new plant, Crimson Sprouts

Crimson Nether Fortress:

Crimson Piglin Bastion:

BASALT DELTAS:

Biome Rework: Basalt Deltas now generates basalt blocks on the roof of the biome, it also has Ash blocks generating in the lava oceans, Blazes now spawn there as well, alongside a new miniboss, the Hovering Inferno (Sidenote, theres no Basalt Deltas Bastion because Bastions dont generate in Basalt Deltas)

SOUL SAND VALLEY:

Biome Rework: Soul Sand Valley now gains a ton of new plants, spikes and Skeleton Wolves, wither skeletons also now spawn there

Soul Nether Fortress:

Soul Piglin Bastion:

NETHER WASTES:

Biome Rework: The Nether Wastes has been completely changed, it has spikes everywhere, a new subbiome called the Cinders, Zoglins also now spawn naturally there.

(sidenote, the normal nether fortress spawns here)

Nether Wastes Bastion:

NETHER LAYERS:

The Nether now has 3 different layers, the Upper, Lower and the Middle (middle being the normal nether experience):

(sidenote: Biomes may change how the layers generate, images shown are the Nether Wastes since it shows the most of the layers)

Upper Nether: Upper Nether contains a new block, Infernalslate, an orange variant to deepslate, you can also find tons of ores that spawn in the Deepslate level of the overworld, like Diamonds and Iron, as well as a brand new ore, Ruby (Layer starts at Y=95 and goes to height limit)

MAGMA CRYSTALS:

you may depending on the spot your in stumble across these crystals in the shape of a flower, these are primarly used for building and making Calibrated Fire Charges, which you can throw, depending on the crystal used, the effect will be different:

Plasma Magma Crystal: spawns in Lava Oceans:

Infernal Magma Crystal: Spawns in the Upper Nether

Eldritch Magma Crystal: spawns Rarely in the Lower Nether

STRUCTURES:

Theres over 13 new structures that spawn in the Nether, heres some of the coolest ones:

Abandoned Lab: the Abandoned Lab is an extremely large structure that has Mechs of Mutation and Tantalum Drones guarding it, it can give an absurd amount of tantalum and iron if you manage to survive, it also has its own exclusive and usful item, Virolite

Ghast Nest: the Ghast Nest is where you can find the sleeping irradiated ghast:

Inferno Trial Chambers: the Inferno trial chambers has a series of rooms with trial spawners and vaults, it has its own exclusive key and the trial spawners when ominous have a completely unique set of things it spawns. theres a ton of exclusive loot here like for example, an item that turns your arrows into bats that attack nearby mobs and players (that arent holding a bow) (note it can be found in any nether biome)

Skeleton Hotel: the Skeleton Hotel is a giant structure that has an absurd amount of skeleton and wither skeleton spawners, chances are you will die here unless you come in with extremely overpowered gear

Cinders Labyrinth: The Cinders Labyrinth is a giant cinderplate tower filled with secret rooms and is the only source of brimstone, it has its own crate that can be unlocked via a key dropped from the Brimstone Apprentice (note it can be found in any nether biome)

Piglin Mineshaft: This is the most dangerous structure in the add-on because of how many piglins there are in it, however the loot is nothing to scoff at, theres chests riddled throughout the whole structure filled to the brim with good loot

Soul Blacksmith: Inside is a new crafting block, the Soul Forge, its used for crafting a ton of items in the mod

Crimson Forest Houses: theres warped versions of these homes too

Giant Sword in the Stone: This Structure contains 4 chests, the middle chest has the best loot, this structure also has a Red version

Basalt Magma Base: This structure contains 1 hidden chest

QUARTZ GEODES: this addon also has 2 new variants of nether quartz, Rose Quartz and Soul Quartz with their own blocksets to go along with them, geodes are added so you can get a ton of nether quartz in bulk

Rose Quartz: Spawns in Crimson/Warped Forests

Soul Quartz: Spawns in Soul Sand Valleys

Nether Quartz Geodes: spawns in Basalt Deltas and Nether Wastes

MOBS:

MOBS:

Infernal Cyclord: Infernal Cyclords jump towards the player, if they land on or nearby them, they spawn a small blast of fire in the surrounding area, knocking back anything except itself back, they drop blazing wind charges apon death

Fleshy Eye: the Fleshy eye can spawn in the nether wastes, its a flying melee mob, it summons babies occasionally when attacking you

Irradiated Eye: the irradiated eye is a version of the fleshy eye, except it deals poison and explodes on death, its babies also explode

Wrathnar: Wrathnar is a trader mob that occasionally spawns in any nether biome except the irradiated wastes, he sells several nether themed items, due to him being a humanoid mob, he gets attacked by everything that a player gets attacked by, but luckily, he has a giant sword to defend himself (his sword can be obtained in the Inferno Trial Chambers)

Brimstone Apprentice: this is a charred humanoid mob that summons magic flames, she spawns in the Cinders Labyrinth Structure that spawns in any biome, she also can interact with Brimstone Soul Surger blocks and summon her own souls to attack nearby players from the location of the brimstone soul surger

Charred Allay: the Charred Allay is a tamable mob thats also found in the Cinders Labyrinth, when tamed you can give it any weapon and it will use it to fight for you, before you tame it, you can give it a Magma Crystal Shard and itll transform it into a new version of itself that has a different bonus

Infernal increases its movement speed
Plasma increases its damage
Eldrich gives it full knockback immunity

Magma Crystal Forms:

Tantalum Drone: Tantalum Drones attack all players via melee attacks, they spawn in the Abandoned Lab

Sad Ghastling: a smaller version of the ghast that shoots mini fireballs

Irradiated Skeleton: Irradiated Skeletons shoot piercing nuclear bolts, if they hit something they leave behind toxic gases:

Irradiated Zombified Piglin: hostile towards players, when they attack they create explosions

Scorched: Scorched's shoot blazing wind charges at players

Spore Creepers: Spore creepers look similar to normal creepers, however when they explode they leave behind a deadly spore cloud instead of your usual explosion, this cloud deals 5 armor peircing damage and is very deadly, these creepers drop Gunpowder just like their normal counterpart

Nether Creeper: this one is identical to the normal creeper except the explosion is weaker and leaves fire behind, drops gunpowder

Nether Mooshrooms: Nether mooshrooms function identially to normal mooshrooms, except theyre fireproof and can be interacted with bowls from the nether wood to give nether mushroom soup, you can interact with them with a bucket and also get a Lava Bucket back, you can strike them with lightning to change their forms just like the normal mooshroom

Nether Cow: only thing different from a normal cow is that its fireproof and yeilds lava when using a bucket

Piglin Miner: This mob spawns in one structure, it can break most nether related blocks (except netherrack cause of lag purposes) he typically uses a gold pickaxe

Magmite: Silverfish that spawns in lava oceans, it ocasionally leaves the lava to attack players

Magma Golem: Magma Golems spawn in lava and occasionally will leave to attack nearby players:

Angry Strider: Angry striders are hostile to everything that isnt a strider

MINIBOSSES:

Ghast Balloon: Inspired from "A Minecraft Movie" the Ghast Balloon carries 2 piglins both holding crossbows, the miniboss cycles between rapid firing arrows at you and shooting fireballs, it spawns in any nether biome Drops your usual ghast loot plus 1 netherite scrap

Hovering Inferno: From the very first mob vote, this mob spawns in Basalt Deltas and is essentally a buffed version of the blaze, it shoots giant fireballs at the player similar to a ghast. Drops 3-5 Blaze Rods plus a netherite scrap

Mech of Mutation: the Mech of Mutation can be found inside the Abandoned Lab structure, it shoots a giant laser when you're more than 8 blocks away, the laser can pierce through walls and deals extreme damage, when you're close to it, it switches to melee attacks

BOSSES:

Mutated Nuclear Ghast: Mutated Nuclear Ghasts can be found sleeping on a structure, when theyre asleep theyre completely invincible to all damage, to awaken them, you need an Infernal Death Whistle which is sold by Wrathnar, it can also be obtained via Wrathnars mystery bag also obviously sold by him, when you have the whistle, go up to the ghast and use it near it. it will awaken and begin the fight, he shoots a large variety of nuclear fireballs at the player, he occasionally can summon a swarm of baby irradiated eyes to help him, and cause the whole biome to begin exploding, he also can randomly poison all mobs near himself, when killed he drops a Nuclear Ghast Tear, which is used to make Doomsday potions, the Nuclear Irradiator which can kill nearby mob types of the players choosing, and a Xeno-Nuke which is a powerful form of TNT that summons mini versions of the blast on nearby mobs of the first blast.

Pyrogen: Pyrogen is a unique boss thats spawned by covering a Tempered Forge block in Lava in the nether (Crafted in the Soul Forge which is found in a structure in the Soul Sand Valley), Pyrogen has a large array of attacks, including shooting fireballs, summoning Evocation fangs and using his orbiting weapons around him to turn himself into a sawblade, he drops a Pyro Forging Template, a special item used in the Soul Forge to craft gear thats better than Netherite

NEW WEAPONS, TOOLS AND ARMOR:

Battle Axes: they do +4 more damage than swords, however when you hit something your hit with weakness 3 and slowness 2, reducing your damage and movement speed by a lot, they also can pierce shields

Caltrops: Caltrops are a throwable weapon that when they land, they deal damage to anything that walks into them, similar to a spike

Emerald Items: Emerald items? in a Nether Update? yep, the tools and weapons are just as good as iron except have the same durability as diamond, the armor also has more defense than iron

Citrine Items: Citrin is a new ore found in the Basalt Deltas biome, it has the same stats as diamond but lower durability

Tantalum Gear:

Tantalum is an ore thats found in the Irradiated Wastes biome either through the abandoned lab, structure chests or as an ore. the ore itself is primarly used for building Tantalum is slightly better than iron stat wise

Ruby Items: now this is why Emerald items actually exist if your still wondering why theyre here, Ruby items are the upgraded version of emerald items, they have the same stats as diamond, except the tools which have the same stats as Netherite, they have double the durability of diamond items, and serve as an alternative to Netherite

(Note Ruby Ore is found inside of the higher parts of the nether, the Forging Template is found in Crimson Forest Structures and Nether Mineshafts, to craft the items you need a Soul Forge)

Obsidian Items: Obsidian items are an upgrade to Iron items, they have the exact same stats as diamond, aside from durability which is 4x stronger than diamond durability

(Note Forging template is found in obsidian related structures, items are crafted in the Soul Forge)

Virolite items: Virolite is a crystal thats found exclusively in the abandoned lab structure, its forging template is also exclusively found there, it has better stats than diamond, tools have high crushing (multiplies mining speed against modded blocks)

Pyro Items: Pyro Items are the strongest set of equipment in the addon, theyre the upgrade to netherite items

(Note Pyro Forging Template is dropped by Pyrogen (scroll up for spawning) and the items are crafted in the Soul Forge)

Potions:

Infernal Potion: gives totem effects when drank in lava
(brewed with Infernal Magma Crystal)

Plasma Potion: gives a lv2 potion effect for 3 minutes, the effect is dependant on the nether biome the potion was drank in, the potion has no effect when drank in any biome outside of nether ones
(Brewed with Plasma Magma Crystal)

Eldrich Potion: Summons deadly souls to attack all nearby entities including yourself
(brewed with Eldrich Magma Crystals)

Fatal Poison Potion: Inflicts fatal potion
(Brewed with Radium Dust, has a splash version)

Doomsday Potion: Inflicts all negative potion effects for 15 seconds)
(Brewed with Nuclear Ghast Tears)

Tempered in Flame (Nether Overhaul + New Biome)