The House of Wolves expansion that comes out for Destiny later this month won't include a new raid; instead, its endgame content is focused on a new mode called Prison of Elders. This morning, Bungie outlined what exactly the new mode entails in a livestream event.
Prison of Elders is a horde mode that becomes available to players once they've finished all the House of Wolves story missions. Players are pitted against increasingly challenging waves of enemies, culminating in a boss fight, with randomised modifiers (both good and bad) introduced at the start of each round. Additional objectives, like “defuse these three mines before they explode and kill everyone,” are also randomly generated.
The standard Prison of Elders mode is level 28, and has a matchmaking function, but there are also level 32, 34, and 35 challenge modes that require players to bring their own fireteam. These challenge modes don't have the randomised modifiers and objectives; instead, these are predetermined for each challenge.
House of Wolves comes out on May 19. As well as the Prison of Elders, it includes a new player-vs-player event called the Trials of Osiris, a new strike called The Shadow Thief, and new story missions and multiplayer maps. House of Wolves will also see the loot upgrade system getting a major revamp.