Bungie has detailed more of Destiny’s next expansion, House of Wolves, ahead of its May 19 release.

The Strike included with House of Wolves is called The Shadow Thief. It takes place on the Moon, but features Fallen enemies and a boss that’s a “notoriously cutthroat Fallen mercenary” called Taniks.

Once you finish all the story missions in the expansion, you’ll get access to the Prison of Elders, a co-op arena mode that serves up a series of procedurally-generated battles across many of Destiny’s toughest alien races, including Hive, Cabal, and more.

It’s divided into four parts: a level-28 base arena that you can play over and over again for Vanguard Marks and Reputation (among other rewards), and three challenge modes that are level 32, 34, and 35. The base mode will have matchmaking; the challenge modes won’t.

Survive it all and your fireteam will gain access to the Queen’s treasure room. Devoted Prison of Elders fans can also unlock special challenges at levels 32, 34, and 35.

Bungie details the Prison of Elders from Destiny expansion House of Wolves