It would have to be the Mo'Creatures Mod!But if you asking what i would make/add,it would be (this is just a random name ) Zentro,which is like Heaven,where you can get cloud blocks and stuff!To make it you have to have snow blocks,and it has to be sideways (like the End portal) and the boss is like a giant Air Golem that you have to go behind and and not let it crush you(or something) or blow you too high,but when it blows you high,you can attack it on it's head and kill it like that,and the weapon of choice (like the Enderdragon is the Bow & Arrow) is a a Fishing Pole and Sword (fishing pole to pull it in,sword to hit it) and when you beat it,a portal (like when you beat the enderdragon) appears,except it's white,and you go into it,and the Universe talks again and you have achieved a higher level of understanding!now THAT is what i call an Idea! (and i just made this up while responding to it )(thanks hunterbeebe for Aether because that suits it perfectly )