Entering this zone begins the quest Till the Blood Runs Clear.
The Hidden Compound (also called the Ring of Blood or the Slaver's Compound) is randomly found in Maj'Eyal. It is a three-level zone, with the first two levels made up of a many small columns and partial walls, leaving many slightly hidden areas when navigating. The only enemies found are Slavers and Enthralled. Each Slaver has 2 Enthralled slaves. If you kill a Slaver, his Enthralled will become free and help you out. You get an achievement for freeing 30 slaves.
On the third level of this compound is the Ring of Blood an open arena, with a non-hostile boss (the Blood Master) near the entrance, and an Orb of Command on the opposite side. After speaking with the boss, you can pay 150 gold to use the Orb of Command. This will put you in control of a Brawler inside the arena. If you can defeat 10 enemies, you will unlock the Brawler class and receive the artifact ring Bloodcaller. You may kill the Blood Master afterward, if you wish.
To win the open arena, concentrate on using double strikes to increase combo points, and then using uppercuts to stun opponents. Use body blow if you need to retreat a bit to heal up. Try to kill the enemies quickly, because more enemies will continue to flood into the open arena. However, when the situation demands it, don't be afraid to trigger your Regeneration infusion and retreat. Also, there are 3 unallocated stat points that you can assign at any time.