Forgotten Realms: Adventures in Faerûn is a campaign sourcebook for the Forgotten Realms using the 5th edition (revised) Dungeons & Dragons ruleset published by Wizards of the Coast, alongside Forgotten Realms: Heroes of Faerûn. Oriented toward dungeon masters, it presents adventure ideas, monsters, and magic items, and an introductory adventure, “The Lost Library of Lethchauntos”.