Pathfinder 2E's next major expansion will be Secrets of Magic, a new rulebook containing two new classes. Yesterday, Paizo announced plans to produce and publish Secrets of Magic in 2021 as their next major release. Details about the book were sparse, but publisher Erik Mona confirmed that it would include new versions of the Magus and Summoner classes. The Magus is one of Pathfinder's most popular classes, a hybrid warrior-mage with tons of versatility and abilities. The Summoner class is a casting class that, as its name suggests, focuses on the ability to summon and control various monsters to the battlefield. The Summoner also bonds with an eidolon that grows in power as the Summoner does.
Pathfinder 2E is a new version of Pathfinder, a fantasy tabletop roleplaying game created as an alternative to Dungeons & Dragons. While the two games have some similarities, Pathfinder 2E retooled its entire game experience to provide more character customization and a streamlined combat system focused on three actions per turn. Notably, Pathfinder 2E also did away with the concept of "race" in their game, replacing it with customizable ancestries that gain abilities as they level up.
Secrets of Magic will be the second major expansion for Pathfinder 2E, which launched back in 2019. Yesterday, Paizo officially released its Advanced Player's Guide, which added four new classes and five new ancestries, along with rules on archetypes and tons of new feats. Paizo also announced that it would release the Bestiary 3 in 2021, which would round out its "core" trilogy of monster books. While more monsters will be added to Pathfinder 2E, they plan on switching to a different format for monster books.
Secrets of Magic will be released in summer 2021, coinciding with next year's Gen Con.