When Bhael was initially summoned he started causing death and destruction around him with his own personal power. However, within the first day of his avatar walking the surface of Kaelaross, he decided it was much easier for him to unleash his minions of Chaos to do the killing and wrecking for him. Thus he began to create Chaos Portals in each city he visited. Each portal connected that city to a plane of Chaos. The portals appear as glowing upright discs of mystical energy. The size of a Chaos Portal varies, but is usually between 6' and 12' in diameter. Some are large enough for adult red dragons, cloud giants and other huge creatures to pass through. They are two-way, so anyone brave or foolish enough to step through a Chaos Portal can find himself on the other side, in a Plane of Chaos. As long as they survive the experience, they can use the Chaos Portal to step back into the Material Plane. However, they are not windows - you cannot see what is on the other side without passing through.
Creatures on the Plane of Chaos are attracted to the Chaos Portal and will pass through more readily than expected - it is possible there is some sort of Sympathy spell involved. Thus when the Chaos Portals were first created there were initial floods of invading chaotic creatures, attacking and overwhelming the inhabitants of the cities. Those Chaos Portals created during the Summoning have been open for 50 years, and although there are still some chaotic creatures still emerging, they are far less frequent and more sporadic than back during the Summoning.
Both creating and closing a Chaos Portal is difficult and requires a great deal of magical power. Generally speaking opening a Chaos Portal involves a Gate spell, combined with Permanence and a carefully worded Wish spell. Bhael either demonstrated an unfathomable level of magical power, or else some sort of innate ability, as he seems to have created dozens, maybe hundreds, of Chaos Portals in a matter of weeks.
Closing a Chaos Portal is just as difficult, and requires a high-level cleric (at least 15th level) casting Dispel Chaos (or Dispel Evil if you don't use that variant) while a very powerful magic user casts Close Gate (the reversed version of a Gate spell) and either the Cleric or the Magic user casting a Wish spell, wishing the Chaos Portal to be closed permanently. Not many people in Kaelaross know this, and the problem was highlighted in BY1590 when forces from Teiglin tried to liberate Erkhart, but they found they could not close the Chaos Portal, so they had to retreat.
The exact number and location of Chaos Portals is unknown to anyone except the gods. However, there is a list of known Chaos Portals that may be added to. All of these have been created by Bhael during the Summoning and most were created in crowded cities for maximum death and disruption.
- Erkhart, former capital of Teiglin, has a Chaos Portal connected to Hestoris
- Urdus, former capital of the Duchy of Urdus, now underwater, has a Chaos Portal to Toldaar
- Aerisport, in the Godsblood Straits, has a Chaos Portal connected to Carceros
- Maquosmouth, in the Godsblood Straits, has a Chaos Portal connected to Hestoris
- There is probably a chaos portal in the Twisted Hills, but its location is unknown.