Power school

Your in a world where there's powers, this world has NO POWERS but to get them is by proving your self defeating 100 mobs, mobs are just evil creatures and it's normal to kill them to level up, after getting your power there is a rarity, common= 94% rare=4% and legendary=1% but somethings not right, there is one missing 0.01% of a rarity and scientists was 100% sure that the rarity was right! So there is an unknown power NOBODY HAS EVER GOT NOT IN DECADES, you need to kill 100 mobs to level up AND NOBODY HAS EVER GOTTEN TO LEVEL 999