New realm with new boss and mob

What if Minecraft had another boss and a new realm to explore. What if that realm was inside a mountain Fortress and in order to get in you had to have a special new item that can be crafted using three blaze rods placed in the last spot on the first row the second slot in the second row then the first slot in the last row and then two iron one in the third slot of the second row one in the second slot in the last row to make a key that will unlock the fortress then inside the fortress it would have 10 different Floor with each floor having however many rooms you want to add with chest with random loot in a select few and in each can have a combination of all the mobs or at least two or three different mobs and in the last room on each floor there will be a stair case with the second to last floor containing a whole new mob called the hell hound that will drop a key to the third boss and  then you get to the last floor containing one giant set of double doors where you will use the key that you got from the brand new hostile mob and enter a giant room where the new third boss Cerberus could be where you can choose to kill or tame him/her. Upon defeating Cerberus you can get a tooth that can craft a sword with special enchantments like easy mob taming sharpness 4 and mending and new effect called brittling which is basically poison but for skeletons.