In the Southern Expanse, there is a secret arena with several leagues you can attempt. If you choose Hell Gate you will encounter an endurance fight for Gladiators 18 and above. The first four fights consist of four Summoners of the same realm; first air, earth, fire, then water. The last fight is a Summoner named Sarenenutet (the same summoner you killed in the Saraa Izel quest Mysterious Tablet). Kill him and you will receive some interesting items that you will never find in any store. After completing the fights, go to the far southeastern corner of the desert. You will encounter Usus. He will tell you a small tale, then each warrior you actually used to fight the Hell Gate league will each receive an attack called Hell's Fury. This is an area affect attack that does massive damage, killing nearby enemies instantly. To find this league, try running around at night, pressing A (as if searching the beach). Note: You must be standing still while pressing A to search.