It contains updates for the 3.5 edition of the fictional Dungeons & Dragons universe for some material from the Planescape campaign setting, along with new races, equipment, spells and feats for characters adventuring on the Planes.
Bruce Cordell admitted that "the Planar Handbook is ambitiously titled, which means we had to be selective in covering only those things we believed would be most useful to plane-venturing players. Essentially, after a few concept meetings involving the designers, as well as other Wizards staff members, the lead designer for the project (me) put together an outline of topics and divvied up the work among all the assigned designers."[1]
