"Heart of Thorns" is the first expansion for the MMORPG Guild Wars 2, released in October 2015. It introduces the Maguuma Jungle, a new region filled with diverse environments, creatures, and challenges. Players can explore this vibrant area while uncovering the story behind the Pact and the threat posed by the Mordremoth dragon. The expansion also features the new Revenant profession, which allows players to channel the powers of legendary figures. Additionally, it introduces the Mastery system, enabling players to unlock new abilities and skills as they progress through the game, enhancing their overall gameplay experience.