Worlds a Step to the Left - Lucidity
This is a rather interesting world. The core dimension is an Earth, apparently wholly indistinguishable from our own - yet, in their dreams, the people of this planet walk through another land, appropriately called the Dreamlands. External magic has a rather hard time functioning on this Earth, and there is no native magic, except Dreaming and Dreamwalking. Those born in this world or who spend a significant time in it obtain the same potential for local magic.
Dreaming is the process of modifying the Dreamlands, and as such it cannot be said to be an Earthly magic - for the Dreamlands are another dimension entirely, folded around the Earth like a protective shell.
Dreamwalking is the process of slipping between layers of reality. Earth can be imagined as the zeroth level, the center of the bullseye. At each layer up, more becomes possible, and reality becomes less consistent. The first layer is the Dreamlands. The second layer, outside to or above the Dreamlands, is the Magelands. The third layer, outside to or above the Magelands, is the Idealands. The layers beyond the Idealands have neither been mapped nor named by humans.
While objects can be brought between layers, information cannot. A picture taken on one is incomprehensible on the others. Books will show different contents on different layers of reality. Hard drives will become filled with nonsense until you return to your original reality.
In the Dreamlands, sapients can take their Ideal Form with some level of effort. An Ideal Form is what you want to look like, with a nature mostly limited by your own imagination. In the Magelands, the Ideal Form is the default, and it's an effort to take your Earthly form. In the Idealands, it is as impossible to leave your Ideal Form as it is for someone on Earth to take theirs on.
Magic beyond Dreaming becomes possible in the Magelands. The natives have defined schools of magic, but in truth it seems to be heavily influenced by their own expectations and perceptions.
The Outerlands are the highest - and weirdest - levels of reality. In them, the Outer Beings wage war, knocking loose threads of unreality. These threads can become tangled around souls, even those of people currently on Earth. A tangled thread will pull you up one level of reality, and then grant powers in the form of access to higher realities of non-existence. Most of the entangled have access to magic and an individualized power greater than what magic can do while in the Dreamlands. However, not even the entangled can use magic on Earth.
Threads that do not entangle someone will instead entangle a part of a lower reality, changing its nature to be odder, often more in line with the higher reality the thread was dislodged from. Threads alter the very landscape where they land, bringing in snapshots of other realities' definition of what is possible. The scale of a thread ranges from a few dozen square feet to square miles. Gravity might work based on intent. Violence, or even the thought of it, might be impossible. Everyone might have magic - but only within the thread. Thoughts might spill from the minds of those who think them.
A warning for travelers: sometimes, visitors to Lucidity end up with a Lucidity-style soul attaching to them. Usually this is harmless, as it simply hooks you into the native magic system, but it has been known to conflict with the visitors' existing metaphysical status.