You have been chosen as a Planar Warrior, one of the most prestigious ranks you can have. While most of the omniverse is kept on their respective planes, you are one of the few that are permitted to jump between them, fixing problems and slaying monsters. Of course, while the name may imply otherwise, it's not just warriors. Wizards, warlocks, thieves, and completely outlandish things are all quite common. The Planar Warriors have homes everywhere, and act everywhere. So, on which plane do you originate? And, who are you?
Plane of Dreams: An odd world which is fueled by the collective thoughts of the rest of the inhabitants of the multiverse. While it may look nice and fluffy, don't be fooled. It's just as dangerous as other places, and potentially more so than others. Much of its danger lies in the fact that it can use your dreams and nightmares against you. Dreamworlders get +2 to detecting illusions.
Plane of Innovation: A land of clockwork and machines. While the inhabitants themselves, the Gnomes, are quite weak, their artificial bodyguards are not. Beware any heap of junk, for a golem could be lying underneath. Gnomes get +2 to mechanical knowledge.
Plane of Light: A world flooded in blinding light. It is necessary for non-natives to wear a highly powered form of sunglasses to stave off death from sensory overload. Creatures here are generally blind, but have other senses to make up for it. The sentient race here, known as "Angels", are not actually divine beings, but can withstand the light and are often considered to be beautiful compared to other races. Angels get +2 against gaze attacks, and can roam the Plane of Light freely.
Plane of Darkness: An antipode to the Plane of Light, the Plane of Darkness drowns out all non-magical light. Using magical lights reveal that many of the creatures are grotesque forms of creatures from other planes, leading to some believing that it is, in fact, a Plane of Nightmares. The primary sentient race here is known as the Drow, and are at home with the darkness. They cannot be blinded, and possess nightvision.
Plane of Knowledge: A hubworld A land of information and secrets. While magical prowess and unlimited intelligence is possible, mind shattering secrets are also found in this plane. Wildlife is sparse, but they are mostly personifications of knowledge when they do appear. Elves are found here, having come from the Plane of Magic, a sister world to the Plane of Knowledge. They have +2 to knowledge rolls and magic. While the Planar Warriors technically restrict travel between these two planes, the abundance of rifts make it an impossible task.
Plane of Magic: The original home world of the Elves, this plane is host to a variety of magical creatures. In fact, the nature of the planes amplifies spells of all sort. Of course, some danger lies in this, for the ambient magic can overcharge a spell, harming the caster. The landscape is violent and twisting, with special minerals stabilizing the land. Many elves make their home here, getting +2 to knowledge rolls and magic. Rifts are common between this and the knowledge plane.
Plane of Fire: A land of magma and raging fire. Non-natives need protective clothing to survive long here, but in some places, the flames are so intense that no amount of protection makes you immune. Most of the wildlife is elementals and other beings of fire. The natives are Ignans. They have resistance to fire and can roam this plane freely. Citizens are allowed to travel between the planes of fire, water, air, and earth.
Plane of Water: A roiling sea, pockmarked by the occasional island. The entire plane has a tropical climate, and the wildlife is mostly elementals and predatory fish. The natives are the Aquan, an amphibious race. They can breathe underwater and are unimpaired while swimming. Citizens are allowed to travel between the planes of fire, water, air, and earth.
Plane of Air: An endless sky, with some floating landmasses and pockets of gasses dense enough to support a being. Most creatures here are flying, and eggs often defy gravity. The natives are the Aerin. They have the ability to defy gravity for brief periods of time, and often use this ability to get from island to island. Citizens are allowed to travel between the planes of fire, water, air, and earth.
Plane of Earth: A series of massive caves with no known surface. Most of the wildlife are burrowing, and are theororized to make these caverns. Metals are very common, and are the number one export from this plane. The natives here are Dwarves. They can meld in with stone for a short period, and have +2 to identifying stone and metals. Citizens are allowed to travel between the planes of fire, water, air, and earth.
Plane of Terra: A mixed plane, having a variety of landscape. The creatures are equally mixed. Due to the fact that corruption is unusually slow here, it's become something of a marketplace. The primary inhabitants are Humans, and while they themselves are painfully average, they have access to some of the best equipments and prices. They also level slightly faster. The Plane of Terra is special in that all races are allowed to travel to it.
Note that the plane you start on isn't the plane you have to stay on, though staying in other planes for too long can lead to corruption.
Corruption builds up in a creature's body as they stay out of their home plane.
Once a body builds up large amounts of corruption, it will be ejected from the body, causing a growth of some sort, such as horns or hooves. Each corruption taxes the mind of a creature, and too many will make a creature go completely insane, becoming known as a Corrupted. While some corruptions can be beneficial, others can greatly impair a creature. Staying on one's home plane will cause corruption to be slowly removed from the body.
A few plains have odd effects on corruption: The Plane of Terra slows it to almost a standstill, though doesn't remove it. The planes of fire, water, air, and earth are special in that a native from one of those four plains can travel to the others without fear of corruption, though others can still be effected by it. The same is true for the Plane of Knowledge and Elves.
(This can be anything, but the more powerful, the more powerful the monsters you will face will be.