All hostile mobs have been enhanced to have double the movement speed, double the attack damage, and double the health.

This would be bad on its own but some mobs also have special effects:

All mobs which inflict status effects in any way (attacking, shooting, potions) either have stronger or longer effects
Blazes fire in bursts of 72, 1 per tick
Skeletons and crossbow piglins fire bursts of 10

Ultras

Additionally, all hostile mobs have a 1% chance of spawning as ultras. Ultras have 2.5x health, 1.5x the size, always spawn with an enchanted iron or sometimes diamond weapon (assuming it's a tiered weapon) and helmet. Ultras will also spawn two minions with double health and normal size with the same equipment pool every 1-3 minutes (some ultras spawn faster or more but this is generally correct). All ultras can also break a certain pool of blocks that relate to where they spawn (mostly)

Bean firer

Legally distinct in every possible way

Zen gardens

Scattered across the world you will find some zen gardens. The main feature of these gardens is a shelf with some clay, some pots, and some bean seeds.

Sprouts

Crafting a bean seed with a pot will give you a sprout. This can be planted like any normal crop. Harvesting a fully grown one will give you 0-3 bean seeds and one placeable bean firer

Placeable bean firer

It can be placed anywhere (due to the pot). It has high health but you can insta-kill it while holding a shovel. Whenever it dies it'll drop itself but you'll need to pick it up quickly if it died in combat. The bean firer will automatically attack any undead mob it sees, but all undead mobs also attack bean firers. The bean firer will also retaliate if a mob accidentally attacks the bean firer.

Ultra difficulty