Turia said about planes:
"The other planes are ruled by one deity, or collectively by groups of deities. So on the planes they are not restricted from doing what ever they feel like to you. The Cage is the meeting place between agents of the gods, so some rules exist.

"Now here is the really funny bit. Mystara is where no deity has control, where they play the game. Each of them tries to get as many worshippers as they can, so they can win the game and get more status. Thats what the god war is _really_ about; some deity getting upset over losing and breaking the other deities toys. We are all just toys to them. Favoured toys perhaps, but just toys."

• Cage, The: see City, The
• Celesta: Celesta is where several self-professed "good" deities live.
• City, The: there is a gate to this on Limbo, it is activated with clay. Controlled by all the gods, it's a meeting place. There is a gate from the City (one way?) to the maze in Sodjerfjord
• the Raving Fiend aka Black Sail (it has a black sail) is a tavern there
• major library owned by Harmonium there, guarded by centaur-sheep
• Zactal portal: a pool in the cathedral of the Zactars, which was destroyed when Umbra entered it. Tess had been promised use of this by Nimigal. Grumble. This gate also lead to Kasiri, Pandemonium, and Celesta.
• the lower ward is the more chaotic part (Zactar Cathedral is here)
• "jink me" pay me cash to give you some trivial piece of advice
• the Screaming Tower has a gate to the plane of Elemental Air
• the gate to Glantri is in the Hive - a terrible part of the City where people are killed on the open street. Demons and devils go there to fight battles, Harmonium don't touch this section with a barge pole. There are also other gate ways to chaotic places in the Hive. The key to this gate is a live snake.
• Dirkal's Tower: a heavily fortified tower in the Harmonium section. There is an orb at the top which seems to sense Tenarri.
• Faerie Kingdom: a place where the immortal faerie dwell ... you can get there by a special rainbow. The rainbow bridge?
• Faerie Ring: a gate to the Faerie Kingdom. Can get sucked into them apparently and come out a thousand years later.
• gates: there is a gate to the City from a mountain ledge in Glantri. There is a maze in Sodjerfjord with gates to chaos planes and a golden gate to Mirage. There is a gate from the City, where the orcs are, to somewhere in the maze.
• Limbo: get sent here when go to recover someone's soul. There are gates to The City, Mirage, and Alphatia's plane from Limbo. It's the place where the dead go. One has 28 days to get the person before they go through to the plane they have been assigned to go to.
• Mirage: a plane inhabited by "good" deities. You can mentally make 3 objects/day, small (40lb) is easy, large is difficult. 3 living things/day. Food 1/day. Beltharian spell-casting methods work there.
• Mystara: where we are. There are rules of the game ... basic idea is the gods vie to see who can get more worshippers. The gods and immortals(?) may not interpose directly on Mystara if they abide by the rules.
• Niflheim: Hel's plane. Realm of the dead of the Northern Reaches, possibly from some other places too. A dark bitterly cold place, inhabited by undead and frost giants amongst other things. There is a hot river of acid which flows through it ... follow that underground past the guardian (Cerberus? ... Thora will need to correct this reference) and there past a gate with snakes and dripping green acid lies a place where the dead walk restlessly. Hel's castle lies in the middle of this.
• Pandemonium is where several groups of demons live.
• Rainbow Bridge: seems to be a common belief amongst various cultures ranging from Elvish to Northern Reaches. Probably refers to the star gates. The Alphatians also escaped using this. We can probably get back to the Home System via the Rainbow Bridge. This is probably the special rainbow on which one can get to the faerie realm too.