The Rainbow Weapons mod adds new weapons (including my signature Lightning Scepter) and armor to the game, which can be crafted with the rainbow ingot, which is created by smelting the SUPER-RARE rainbow ore.
They're are also Color Cubes, which spawn naturally at night, and the Rainbow Herobrine, which can only be spawned in creative.
There is a new Biome that is covered in Redstone and Emerald Blocks, Obsidian, Glass, and Pig Spawners (that don't actually spawn pigs)