The Skylands

Mobs: 

This mod adds several new mobs including:

The Spirit - a cloud like mob with a single eye, you can use it to ride between gaps in the floating islands because, unlike the end, this dimension doesn't have a gateway to the outer islands.

The Cloudy Cube - a mob that attacks you like a faster version of a Zombie, but if you get to close, it makes you float.

The Floof - a sheep like mob, I added it so you could get food in the dimension.

The City Guardian - a stone mob with 200 health, this mob is best avoided, because it can do 10,000 damage, which can destroy your shield, and kill a player with full Netherite armor in a single hit.

The Amethyst Golem, a mob that can be used to farm amethyst crystals, it also makes the City Guardians avoid you, so bring one on a leash if you want to go near a City Guardian.

The Wildfire - a more powerful Blaze that shoots powerful blaze eyes at you, if you kill it you get the Blaze Eye as a weapon.

And The Slitherlin - a snake like mob that chases you at incredibly fast speeds, if you kill it you get leather.

Blocks:

Cloudy Wood - a new wood type, it has all the blocks that any other wood type would have, slabs, fences, fence gates, stairs, doors, trapdoors, presure plates, and buttons

Cloud Blocks - these blocks are what you get by smelting a water bucket in a furnace, which boils the water into clouds

Solid Cloud - basically stone but it looks like clouds

Cloudy Sand - a sand block that behaves like sand but looks different

The blue grass isn't a new block, it's just the original grass with a tint.

Biomes:

Cloudy Plains - animals are Spirits and Floofs

Cloudy Forest - animals are Spirits Floofs, and Cloudy Cubes

Cloudy Taiga - same animals as Cloudy Forest

Crystal Valley - animals are Amethyst Golems

Sky City - animals are City Guardians

Sky Desert - animals are Slitherlins

Cloudy Swamp - Same as Cloudy Plains

Items:

Blaze Eye - a powerful ranged item that does 15 damage and lights things on fire

Knowledge book - a book that can be found in a structure, and can be crafted with a Totem of Undying to get a book which spawns the Illusioner

Flight Enchantment - an enchantment which you can put on your chestplate, if you hit the C key than it will give you levitation for 3 seconds

Heart of the sky - an item which you can craft from 5 gold ingots in a + shape, it lights the portal to The Skylands

How to enter the dimension:

Build a portal in the same shape as a nether portal, but with Cloud Blocks as the frame, and the Heart of the Sky as the lighter