The Forsaken Lore expansion adds new research cards, spells, weapons, and conditions to vastly improve the replayability and variety of the game. It also introduces Yig, a new Ancient One deemed the Father of Serpents, who is looking to dominate the Earth with the help of new Epic monsters and Serpent People. Forsaken Lore does not add any new mechanics to the game, so introducing it to the base game will cause no headaches.