This invaluable sourcebook provides DMs and players everything they need to create and run planar adventures and campaigns. Complete rules and guidelines for creating characters skilled at plane travel and world-hopping, as well as new prestige classes, feats, spells, and magic items. Comprehensive descriptions of several different portal types, including their traits, characteristics, and game statistics. Rules and guidelines for designing an endless variety of new worlds and planes. Guidelines for altering existing creatures to create planar variants, and complete descriptions of many new extraplanar monsters and allies.