Publisher's blurb: Inside this volume you'll find the following information ... An overview of the Planes of Ash, Ice, Magma, and Ooze, including ways to get there, how to survive, how to get around, and what to avoid A look at the powerful entities on the four planes, including the Slime Lords, the Mephit Monarchs, and Fimbulvinter the White Doom! 13 new monsters, including the belker, dripping crawler, elder thing, border elementals (ash, ice, magma, and ooze), frost salamander, lava shark, mud serpent, ragewraith, swarm of ash rats, and swarm of frostmites! Hazards to avoid across the four Border Elemental Planes, such as chokeclouds on the Plane of Ash, deep freezes on the Plane of Ice, magmafalls on the Plane of Magma, and insect swarms on the Plane of Ooze! 12 interesting sites and treasures to be found across the Border Elemental Planes, such as the Battlefields of Smoke, Bog of the Dead, City of the Elder Things, Throne of Blazeheart, Lost Mire, Slime Lord Tombs, and Tundra Pits! Adventure hooks for all tiers of play! Random encounter tables for the Planes of Ash, Ice, Magma, and Ooze! Three new player options - the Oath of Clarity for paladins, the Ooze Magic origin for sorcerers, and the River of Rage patron for warlocks!