Uncaps enchantment levels on anvils (up to 255). You can blacklist enchantments in the config.
Rare overpowered mob spawns with random enchants and potion effects that are beyond vanilla limits.
Extreme natural disasters like volcanoes and earthquakes and sinkholes. Inspired by the general disasters mod.
Many customizable Mob Events and AI behaviors aimed at making the game very difficult. Server-side only!
Mobs can use and ride boats and attack while inside them!