Additions:

1. Added 'in_cave' criteria to check if an entity is underground (the 'in_cave' criteria is either: being at Y=-64-62; being in a 'cave_air' block; being in a Mineshaft/Stronghold/Trial Chamber/Ancient City; being in a (Lush/Dripstone) Cave/(Deep Dark) biome);
2. Turtles now apply 10 seconds of Water Breathing to Players in a 5 block radius (both entities must be in water source blocks);
3. Wandering Traders struck by lightning will now convert to Illusioners;
4. Zombies/Skeletons/Bogged/(Cave) Spiders/Creepers can now spawn with an infinite 1.21 effect in certain locations (10%; Weaving - Mineshafts; Infested - Strongholds/mountain biome caves (must meet the 'in_cave' spawning criteria while in a mountain biome); Oozing - (Mangrove) Swamp);
5. Added Sad Ghastlings (10% of Ghasts; drop 0-1 Ghast Tears without Looting; (max) health - 2.5 from 10; follow range - 80 from 90; shoot Small (Blaze) Fireballs);
6. Added baby Creepers (5% of Creepers; drop 0-1 Gunpower without Looting instead of 0-2; (max) health - 5 from 20; explosion radius - 1 from 3; movement speed - 0.35 from 0.25);
7. Added baby Spiders (10% of Spiders without passengers; don't drop String; (max) health - 4 from 16; follow range - 8 from 16; attack damage - 0.5 from 2; movement speed - 0.5 from 0.3; step height - 0.3 from 2);
8. Added baby Bogged/Strays/(Wither) Skeletons (10% of spawns that aren't Horsemen; drop Bone Meal instead of Bones & no Arrows; spawn with (Tipped) Arrows/Sticks instead of Bows/Stone Swords; (max) health - 4 from 16/5 from 20; movement speed - 0.28 from 0.25);
9. Added "adult" Phantoms (90% of Phantoms; deal 5.5 hearts of damage; drop 0-1 Bones without Looting on top of the Phantom Membrane drop);
10. Some adult hostile mobs can now drop additional items (Same chance as Gold Ingots from Ziglins & must be killed by a Player; Creeper - TNT, Spider - Cobweb, Husk - Sand, Stray - Ice, Bogged - Vine, Ghast - Fire Charge, Phantom - Rotten Flesh);
11. Added (baby/Cave) Spider/Creeper Spider Jockeys (10% chance for babies, 5% chance for Cave Spiders if meeting 'in_cave' criteria/Creepers if not meeting 'in_cave' criteria);
12. Added baby Spider Cave Spider Jockeys & Skeleton Blaze Jockeys (10% chance);
13. Some mobs without vehicles can now mount certain nearby mobs without passengers (10% chance every second, 2-block radius; Creeper -> adult Spider | baby Creeper -> Cave Spider | baby Spider -> (adult/Cave) Spider | Skeleton/Bogged/Stray -> adult Spider/Pig/Sheep/Cow/Skeleton Horse | baby Skeleton/Bogged/Stray -> Cave Spider/baby Skeleton Horse | (Wither) Skeleton -> adult Hoglin | Stray/Skeleton -> adult Goat | Stray -> adult Polar Bear | Skeleton -> Blaze | Drowned -> adult Turtle/Skeleton Horse | baby Drowned -> baby Skeleton Horse/large Salmon | Zombie (Villager)/Husk -> adult Spider/Zombie Horse/Cow/Sheep/Pig | baby Zombie (Villager)/Husk/Drowned -> adult Zombie (Villager)/Husk/Drowned | baby Zombie (Villager)/Husk -> Cave Spider/adult Chicken/baby Zombie Horse | Evoker/Pillager/Illusioner/Witch/Vindicator -> Ravager);
14. Added 6 new Pig variants from Minecraft: Earth (ATTENTION! This doesn't affect where Pigs can spawn. The textures were adjusted to work in Minecraft. Biomes/structures: Pink Footed - Old Growth Taigas, Taiga Village; Pale - Windswept (Gravelly) (Hills/Forest), Pale Garden, Meadow, Stony Peaks; Mottled - Savanna biomes; Piebald - Badlands biomes, Desert (Village), Warm Ocean, the Nether; Spotted - (Old Growth) Birch Forest, Plains Village; Sooty - (Dark/Flower) Forest, Lush Caves);
15. Added 9 new Cow variants from Minecraft: Earth (ATTENTION! This doesn't affect where Cows can spawn. The textures were adjusted to work in Minecraft. Biomes/structures: Sunset - Jungle biomes, Mangrove Swamp, (Deep) Lukewarm Ocean; Dairy - (Old Growth) Birch Forest, Plains Village; Umbra - (Dark/Flower) Forest, Lush Caves; Pinto - Badlands biomes, Desert (Village), Warm Ocean, the Nether; Cream - Savanna Village; Wooly - (Snowy) Taiga, Grove; Ashen - the End, Deep Dark, (Deep) Frozen (Ocean/River/Peaks), Snowy (Plains/Beach/Slopes/Villages), Jagged Peaks, Ice Spikes; Cookie - everywhere where other variants aren't; Albino - 5% of Cookie/Dairy/Temperate Cows, Pale Garden);
16. Added 6 new Chicken variants from Minecraft: Earth (ATTENTION! This doesn't affect where Chickens can spawn. The textures were adjusted to work in Minecraft. Biomes/structures: Skewbald - Old Growth Taigas, Taiga Village; Bronzed - Windswept (Gravelly) (Hills/Forest), Meadow, Stony Peaks; Gold Crested - Savanna biomes; Amber - Jungle biomes, Mangrove Swamp, (Deep) Lukewarm Ocean; Stormy - (Old Growth) Birch Forest, Plains Village; Midnight - (Dark/Flower) Forest, Lush Caves);
17. Added 6 new Eggs (Skewbald - Beige; Bronzed - Purple; Gold Crested - Yellow; Amber - Red; Stormy - Gray; Midnight - Black);
18. Undead Horses can now be equipped with Horse Armor (it doesn't render the armor at the moment, but I will look into it);
19. Horse Armor now protects Undead Horses from sunlight.

​Changes:

1. ​Vanilla Phantoms have been reclassified into baby Phantoms & nerfed (10% of Phantoms; (max) health - 5 from 20; same size as vanilla Phantoms);
2. Buffed Spiders (Changed step height to 1.2 from 0.6);
3. Buffed Ravagers (Changed step height to 1.5 from 1);
4. Nerfed Blazes (Changed follow range to 40 from 48 & attack damage to 4 from 6);
5. Nerfed Ghasts (Changed follow range to 90 from 100);
6. Nerfed Cave Spiders (Changed step height to 0.3 from 0.6, (max) health to 6 from 12, movement speed to 0.2 from 0.3 & attack damage to 1 from 2);
7. Nerfed Strays (Changed (max) health to 16 from 20, movement speed to 0.22 from 0.25, burning time to 2 from 1 & follow range to 12 from 16);
8. Nerfed Husks (Changed armor to 1 from 2, movement speed to 0.2 from 0.23 & attack damage to 2 from 3);
9. Baby Camels no longer replace 5% of adult Gold (Desert) Rabbits;
10. Skeletons are now replaced with Pillagers in Mansions;
11. Endermen are now replaced with Slimes during rain & Breezes during thunderstorms (the Endermen must spawn in the Overworld under skylight in order to get replaced; the slimes are size 0 (small); doesn't work in Desert/Badlands/Savanna biomes);
12. Chicken in Zombie Jockeys that spawn underground (meet 'in_cave' criteria) have been replaced with Cave Spiders;
13. Chicken in Drowned Jockeys have been replaced with large Salmon;
14. Chestnut Wolves now spawn in both Old Growth Taigas;
15. Black Wolves now spawn in Dark Forests (13.89% of Pigs in the biome will be replaced by them; 10% of the Wolves will spawn as babies);
16. Temperate Pigs no longer spawn in ((Old Growth) Birch/Flower/Dark) Forests & (Plains/Taiga/Snowy) Villages;
17. Warm Pigs will now replace vanilla Pigs in Jungle biomes, Mangrove Swamp, (Deep) Lukewarm Ocean (ATTENTION! This doesn't affect where Pigs naturally spawn);
18. Cold Pigs will now replace vanilla Pigs in (Snowy) Taigas, the End, Deep Dark, (Deep) Frozen Ocean/River/Peaks, Grove, Snowy (Plains/Beach/Slopes/Village), Jagged Peaks, Ice Spikes (ATTENTION! This doesn't affect where Pigs naturally spawn);
19. Temperate Cows now spawn only in Old Growth Taigas & Taiga Villages;
20. Warm Cows will now spawn only in Savanna biomes;
21. Cold Cows will now replace vanilla Cows in Windswept (Gravelly) (Hills/Forest), Meadow, Stony Peaks (ATTENTION! This doesn't affect where Cows naturally spawn);
22. Temperate Chickens no longer spawn in ((Old Growth) Birch/Flower/Dark) Forests & (Plains/Taiga/Snowy) Villages;
23. Warm Chickens will now replace vanilla Chickens in Badlands biomes, Desert (Village), Warm Ocean, the Nether (ATTENTION! This doesn't affect where Chickens naturally spawn);
24. Cold Chickens will now spawn replace vanilla Chickens in (Snowy) Taigas, the End, Deep Dark, (Deep) Frozen Ocean/River/Peaks, Grove, Snowy (Plains/Beach/Slopes/Village), Jagged Peaks, Ice Spikes (ATTENTION! This doesn't affect where Chickens naturally spawn);
25. Adult Sheep are now different colors in some biomes (Same biomes as the Warm/Cold variants in vanilla; Temperate: Gray -> Green; Cold: Light Gray -> Cyan; Warm: Gray -> Orange).

Fixes:

1. Saddles taken off of Striders/Pigs now maintain their components;
2. Fixed a typo in the v1.0 changelog;
3. Fixed baby Ziglins having too much health when converted from Piglins.

Known issues:

• Horse Armor doesn't display on Undead Horses.