The Shadow Realm

Summary
The Shadow Realm is a parallel realm to the material plane, but everything is switched. Colors, voices, appearances. Say a fair looking woman was singing a sweet melody in a field of brightly colored flowers. It would appear in the shadow real as an ugly demon shouting angrily. Just like how a demon would look and speak like an angel. You have an avatar in the shadow realm and it walks around just as you do in the normal world. Remember liches usually have a strong connection to the shadow realm.

Inhabitants of the Shadow Realm
Just as in the normal world there are beasts and intelligent things that call the shadow realm home. They usually don't have an avatar in the normal world. If you are ever in the shadow realm beware of these things. Demons and devils also commonly use the shadow realm to move around for they can materialize there.

Getting there and Back Again
To get to the Shadow Realm all one must do is think, well meditate. Many monks can do this with ease and most knowledge institutions can teach students how to get there. Numerorean Humans also learn at a young age how to use the art of "shadow walking". There are also mystical objects that have been enchanted that can "drop" people unexpectedly into the Shadow Realm. To leave one must only focus on the normal world and deeply imagine what it should be. You can technically pull people or be pulled into the shadow realm with creative work.

Movement in the Shadow Realm
Usually, someone from the normal material plane would not be able to separate from their physical body in the shadow realm, but it is an ability that you can be trained for. The Numerorean Humans are usually trained from a young age how to do it, also many monks and teach themselves how too.

When you do move in the shadow realm your physical body remains in place. Sometimes the area that you can explore is limited but sometimes it is unlimited. Beware what you touch in the shadow realm for the slightest disturbance can cause strange things to happen. But if you were to say pick up a spoon in the shadow realm it would have no effect on the spoon in the normal word unless magic made it so that would happen

Combat in the shadow realm is very strange. Two things can fight normally if both are mentally present and be killed as normal, but if someone in the shadow realm attacks someone that is not mentally in the shadow realm they can not harm them unless they have special weapons such as blood daggers. You have all of the items that you have on you in the normal realm, and magic operates normally in the shadow realm for magic users.