Summary:

Celestial Elites is a datapack that spawns in elite mobs with randomized abilities in your survival world. The abilities are made to fit within vanilla gameplay and aims to be challenging rather than annoying. You can also find rare drops from these elite mobs that have unique effects. This datapack requires 1.20.4 to function!

Feature List:

36 different modifiers that can appear randomly on monsters, effects of these ranging from transforming nearby mobs into horrific distortions to tearing open a rift that deals heavy damage.
5 different tiers of elite mobs which is decided by how much modifiers they recieve. Some mobs might get additional boosts as tier increases.
A dynamic difficulty system that adapts to your difficulty setting and play time as well as factors like altitude or biomes.
All elite mobs can drop useful loot, they even have a small chance to drop unique loot (that can't be obtained elsewhere!) depending on the modifiers they carry.
Craftable mutagens that can transform normal monsters into an elite mob, be careful while using mutagen-z!
Handbook in advancement tab that explains the function of each modifier.
Optimized enough to maintain a stable tps.

FAQ:

Why aren't elite mobs spawning?
Elite mob have reduced spawn rate at the start of the world, and even lower when you are playing in easy mode. You will see more of them spawn when you survive for longer or by increasing your difficulty.

Where do I find more elite mobs?
Going deep underground or high above, as well as staying in rare biomes (ice spikes plain, for example) increases the chance of elite mobs spawning.

How do I get the rare drops?
By killing elite mobs, high tiered elite mobs have higher chance of dropping them.

How do I tell what modifiers monsters have?
Only one way to find out :)

How do I craft Mutagens?
For Mutagen X, place a water bottle in the middle and place four pieces of gunpowder at the corners and four pieces of fermented spider eye at the edges.
For Mutagen Y, place a water bottle in the middle and place four amethyst shards at the corners and four eyes of ender at the edges.
For Mutagen Y, place a water bottle in the middle and place four end crystals at the corners and four wither skeleton skulls at the edges.

There is a bug, how do I fix it?
Step 1 - do /reload.
Step 2 - restart the world.
Step 3 - Go to the discord for support.

Thanks to the Cartographer datapack by PearuhDox and the Monumenta server for inspiration. Thanks to Forite for beta-testing this datapack.
Discord Link to discuss the datapack and view my upcoming projects: https://discord.gg/Gt62aqpRnR