Fantasy roleplaying games allow an escape from reality. They allow us to play out stories with magic, elves, and dragons that could never happen in the real world. Yet they retain elements of the real world, often taking aspects of real world history and cultures to inspire the peoples and societies that populate them. These elements allow the game to retain a certain sense of familiarity, and a certain sense of reality amidst the fantasy.
But sometimes, you just want to abandon reality altogether, get rid of the familiar as much as possible, and create something truly different. This can be through travel to other worlds or even other planes. Planar travel has been a mainstay of roleplaying since its earliest days. It’s often something only embarked upon by high-level characters who have acquired the greater powers needed to make the jump from one plane to another, but it doesn’t have to be. The old 2nd Edition Dungeons & Dragons campaign setting, Planescape made PCs natives of other planes and incorporated plane-hopping right from first level.
The Pathfinder Campaign Setting first outlined its planar structure in the old Pathfinder Chronicles: Campaign Setting book (later updated as Pathfinder Campaign Setting: The Inner Sea World Guide). The information in that book was later expanded upon in The Great Beyond. But even that book could only provide the barest details. The planes are more than just other worlds; they are entire other universes with enough space in each one to hold millions of entire campaign settings.
Planes of Power is a more recent book that takes a much closer look at just four of the many planes that make up the Great Beyond—specifically the Elemental Planes of Air, Earth, Fire, and Water. Of course, this book can still only scratch the surface of these planes, but it is able to provide enough of a backdrop to whet GMs’ creative juices and allow them to expand beyond what’s presented.