Astral Dimension

Starting from version 1.5, you will need to install Geckolib to run the mod

 The Astral dimension is a broken magical world made up of 10 different biomes. Its peaceful lakes and seas have turned into strange pools of Void Liquid, a substance created by the Void Titan. Walking through this place is risky, so make sure you bring an Elytra.

To enter the Astral dimension, you must construct an Astral Portal. It is similar in shape to a Nether Portal, but composed of at least 10 blocks of Glowing Obsidian. Once built, ignite the portal using Glint and Steel, a handy tool that can also be used later in another dimension.

The dimension is filled with strange lifeforms, from snail‑pig hybrids known as Pigails to odd, fungal beasts called Fatal Shrooms. Players can take on 6 bosses, though only 2 are required to complete the core storyline of the mod.

The first boss you’ll face is the Void Titan. To summon it, it’s highly recommended to head into a Fiery Forest, where large Fiery Mushrooms hide among the trees. Inside these mushrooms are Burning Orbs, which drop Burning Shards when broken.

Combine these shards with 4 Glowstone Dust and an Ender Pearl to craft an Astral Eye.

Throughout your journey, you may come across the Helioos, wandering celestial entities. When you carry both an Astral Eye and a newly discovered item, the Helioos will accept the Eye as an offering. They’ll unveil hidden knowledge about the item you’ve brought before them.

With at least 4 Astral Eyes, you are ready to visit the Amethyst Sanctuary, which is guarded by 4 Amethyst Knights. These knights are fueled by Postrum Eyes, which can be deactivated using your Astral Eyes. Defeat them to earn 4 Amethyst Keys, used to open Locked Blocks. Inside you’ll find chests, your goal is to collect at least 2 Broken Amethyst Shards.

To proceed, delve deep into the Astral dimension and collect 27 Void Gems to craft 3 Blocks of Void. Void Ore generates in the Astral dimension between Y level -40 to -12 in blobs of 1-9. It can drop up to 4 Void Gems without Silk Touch. Beware Void Mycelium, blocks that spawn Void Menaces. These beasts drop Void Fangs, and you’ll need 4 of them.

With these materials, construct a Void Pillar using 2 Blocks of Void and a single Void Mycelium. From there, you can craft an Astral Altar, requiring 2 Glowing Obsidian, 2 Broken Amethyst Shards, 4 Void Fangs, and a Block of Void. Seek out a Void Egg, a structure featuring a Void Portal. Place the Void Pillar atop the portal, and the Astral Altar on the Pillar.

Once you place the altar, get ready for the Void Titan and a big explosion.

Defeating the Void Titan yields a massive amount of Gloomy Obsidian, standard Obsidian, and the Titan Helmet, an item that grants the wearer the Lifesteal effect.
With the Titan defeated, your path leads to the Tormented Mansion, a towering structure from the Sludgy Wastelands. It’s the tallest structure in the Astral dimension, and one of the most rewarding.

Inside lies unique loot… and the "final" boss: the Void Visage, source of the Void itself.
Once you slay the Void Titan inside the Void Visage, its remains drop Void Shards, and Void Gems.

Void Shards can be used to craft:
Harsh Leather Armor: Wearing 1 armor piece grants resistance against Void Liquid. It can be crafted using Harsh Leather and Void Shards
Void Trophy: A cosmetic block that can be crafted by combining any sword, 2 Void Shards, and a Gloomy Obsidian

Staff of Levitation: A ranged weapon that uses Void Gems as ammo to shoot a row of shulker bullets

Void Necklace: When equipped in the chestplate slot, it grants immunity to Void Magma and allows you to walk on Void Liquid, which is transformed into Void Magma beneath your feet. It can be crafted using Void Shards and 4 Rachor Teeth

Gloomy Obsidian: A variant of Obsidian crafted using 4 Obsidian and Void Shards. It can also be used to create the Setback portal

The Visage also drops the Astral Amulet. This tool allows items to be used in unique, beneficial ways while the player holds a special item in the off‑hand slot. It has a durability of 436 and cannot be stacked.

The Void Visage is still active. To truly end it, enter the Setback, a dark realm taken over by the Void that is divided into 8 biomes.
To access it, you’ll need 10 Gloomy Obsidian and a Nanta Star.

Nanta Stars are crafted from 4 Nanta Pearls and a Faded Star.
Find Nantas in pools within Faded Fortresses - feed them Twisted Corals to obtain the Nanta Pearls.

Make sure to defeat a Slurker to earn a Faded Star.

Activate the portal with your Nanta Star and face the Setback.

Whispers tell of a material hidden here, said to surpass even Netherite. Loot ancient structures to uncover the components needed to upgrade your Netherite gear. With your upgraded gear, you're ready to face the 4 remaining bosses.

Huge thanks to dreamcritting for creating an FTB Quests tree that outlines the progression of the mod.

https://drive.google.com/uc?export=download&id=1SHkPWSw43G3qUyg0ypvq9FQDWwOMF8I5

For a full playthrough guide, I recommend checking out the mod's Wiki.