Realm of Crystals
Buried under miles of stone and dirt rests a geodic realm of gleaming crystals and brilliant gemstones. With each colorful jewel radiating with Glow, the Magi of Vicus hold as much, or more, power than the Divine. Of their most advanced schools is their mastery over teleportation. Massive gateways reside within Vicus that lead to almost anywhere in the Cosmos - but with enough warding to ensure that nothing comes from the other side.
Underground, has several different depths. Each one is named after a different type of crystal that allows a different set of magic. All life relies on these crystals.
There is air but you never really see the sky.
Crystalites - Basically crystal golems. Nytherials - Beings of light that use crystals to manipulate the world around them. No manfolk can survive here due to the complete lack of food. Crystal Elementals come in many forms depending on their crystal type. (Like quartz, etc.)
There are no plants, but crystals grow very similar to them and are consumed for the same reasons plants are. Crystals grow via being soaked in a glow-infused liquid that is present in the lower sections of the realm.
All life on the realm is actually crystaline or made of pure light. If you cannot survive off rock, crystal, or Glow you will end up dead.
Glow is found as a pure source of light that reflects and bounces all over the realm. Some crystals are able to hold Glow. Some crystals are so ancient and have been soaking up Glow for so long they could power an entire realm.
Teleportation Magic. Advanced Runes. Lots of light-bending tricks. Not so much in the form of construction as nothing can die from the elements. Farms are consturcted to keep crystals growing efficeintly.
Realm of Crystals
The Earth Realms
The Light Realms