The boss, Raksh, is a red winged dragonwrought kobold wizard 20||paragon 15/sorcerer 5. You will find him scribbling a ritual pattern with orichalcum on a rectangle platform in the middle of a volcano's crater at the bottom of his demi-plane. To reach him, you will have to go through all of his generals first, through all the other demi-planes. His army have, with time, set-up null-fields around these demi-plane, letting you teleport inside each level, but not accross each other.
The first general is a white winged dragonwrought kobold barbarian 16||fighter 16 on top of the island, just before the entry into the demi-planes of Raksh. The middle of the Island have been hollowed out into an arena not unlike the colliseum and in the center of it all is the only entry point to reach the first level. There are also a bunch of lower level fighters and barbarian kobolds, some white dragonwrought but none with wings.
The second level is a 100km long x 100km large x 100 m high library maze filled with books representing all the worlds documented over the years by the [Exchangers]. You will find a few [10-50] sorcerers around, all blue dragonwrought kobolds with good climb skills. There are many ladders and ropes on the shelves of the library to help them move around. The boss of the level is a blue winged dragonwrought kobold Sorcerer 17||Bard 17.After fighting him in the center of the library, you will find a door leading to the next level.
The next level is a forest in which the trees all appear to reach the roof and most of them have a trunk with a diameter of 3 meters (2 cases). With the same dimensions as the library, this forest in which you will find no kobolds, is filled with many creatures who will be hostile to you, as if brainwashed. Once you kill about 10 of them(Wolves, bears, other dire forest critters), they leave and a green winged dragonwrought kobold druid 18||Scout 18 comes to avenge them. It can move through trees at will and will try guerilla tactics as much as possible to not only waste your time, but tire you out along the way. Once you defeat him, you will hear a loud rumble and a tree at the north edge of the plane[The edges of this plane are walls giving the illusion that the forest keeps on going, but stops neatly in a 100kmx100km area.] will open up, revealing the stairs for the next level.
You finally reach the Cathedral's level. In this level, all you can see are stone walls, from what appears to be the floor up to the ceiling of the plane. If you try to break through the stone walls, you will find force walls inside of them. The whole level is a maze with a cathedral dedicated to Tiamat at the end. Inside this maze you will find holes in the ground filled with water, those are tunnels that could help you or give you more troubles. Inside of these holes, you will find some of the last living dragons of this world, black dragons who serve the dragonwrought kobolds and who will do everything they can to stop you(You can find up to 35 black dragons inside these holes if you look for them, but you will most likely meet less than that, as the maze is so big.) Once you reach the end of the maze, if you do, you will find the cathedral dedicated to Tiamat. You will hear a loud rumble and many black dragonwrought kobolds will come out of the cathedral as it is torn apart by a growing, black winged dragonwrought kobold. It is Cleric 19||Paladin 19. You can try fighting it[Cool points if you somehow defeat this monstrosity of theoretical optimization:
http://community.wizards.com/content/forumtopic/2478051] but if you give it one round, it will destroy the floor by failing to touch you, then you'll both fall through the floor. Good luck, you're falling straight towards the mouth of a volcano and that's how the cleric should die.
On this new level, you have a landscape filled with volcanoes, but one is higher and bigger than all the others. If you can see magic, this is where you can guess Raksh is because it is emanating a lot of magical energy, if you can't see magic, well, you can still guess this is where Raksh is.