Centuries ago (in a previous campaign of mine) Asmodeus broke (or was broken) out of the deepest layer of The Nine Hells and began to wage war against the deities who put him there and broke the agreement made in the Pact Primeval. This war became known as “The Great Divide” stemming from the deities all picking sides and waging war openly. The war was waged on many planes and a number of them were nearly destroyed. The war soon became one of attrition where deities were forced to kill one another in order to gain tactical advantage. The result of the war left many gods dead, or powerless. Asmodeus’ fate is unknown as is the majority of other deities. Due to all the warfare there were mass emigrations of races throughout the planes and the effects are still witnessed today. This dispersal of races has lead to a very high increase in half breeds and has also made what were once known as “exotic” races indigenous to many other planes.
During The Great Divide there was a very contagious and deadly force unleashed on the world. Scholars have since named the plague “Taint.” It is a ghastly disease that complete corrupts and destroys living (and sometimes nonliving) matter. Calling it a disease though does not accurately describe the nature of taint. It is not something tangible, but rather a type of presence in objects that destroys it. Down the path of corruption and depravity, victims of taint have reported an increase in power, thereby tempting many mortals into attempting to walk the fine line between taint and madness. One of the early researchers, Troldepus de la Krabdak, did an enormous amount of work investigating the phenomenon before he eventually succumbed to madness from years of working closely with the substance. It was very prominent in the years following The Great Divide, but hasn’t been seen in centuries.
Current Points of Interest
Sigil (The City of Doors, or as some lovingly call it: The Cage) is at the heart of the multiverse and is touched by all other planes, which means portaling into and out of it is possible and happens quite frequently. However when Taint emerged, the Lady of Pain sealed off the city and “evacuated” everyone that still resided in it. However, recently some daring adventurers have finally discovered the secret to reentering the city.
The only way through any of the previous portals depended upon having a planar touchstone (Planar Handbook p 153) in your possession. Touchstones are all associated with important places in the multiverse and nearly all planes have at least one touchstone, the trick is actually reaching it and accomplishing the appropriate task in order to receive one. There are supposedly only 100 touchstones in existence, therefore they have become incredibly valuable. There has been a large market in the various planes for “Touchstone Auctions” where high rollers could go and be presented with a number of various touchstones and bid on them.