Tower Of Classes

In this world everyone is born with a skill unique to them, nobody has the same power. they are also given a rank from 1 to 1,000. There is a tower that people come from all over the world to enter, it has all kinds of mystical beings and creatures and within it laws don't exist except one, only strengh matters. There is 1,000 floors each area the size of a continent yet on the outside are just a room. even among powers everyone can use a special kind of power that rules, aura manipulation is converting life energy into intimidation or power.