Infinity Cave changes the world height from -64 to -128 and adds a new type of cave generation where it all interconnects into an absurdly giant cave system. There are 5 new cave biomes and additions to the Deep Dark biome, making it possible to explore 6 different biomes. Each biome has at least 1 structure with the help from Viavir who is a fantastic builder. However, regular Minecraft mobs do not spawn in these caves. Instead, there is a custom mob-spawning system which is very difficult compared to normal mobs. Infinity Cave is designed for later stages of the game and introduces roguelike mechanics to explore and conquer the caves. Be warned, due to its difficulty, it is suggested to play on Easy mode the first time playing.
Mob Spawning System (AVAIABLE FOR 1.20.2+ ONLY)
There are a plethora of custom items to be obtained with tons more items being planned in the future. Custom weapons and armor are dropped from legendaries-only. Another custom item which is essential to Infinity Cave is Enchantlets. Enchantlets can enchant items with enchants that are not obtainable in vanilla Minecraft. For more information, read the guidebook which is obtained by spawning a custom mob for the first time