Changelings
A race of Higher Beings that can change their appearance at will.
Physiology
As changelings have no fixed forms and can choose their appearance at will, there is no way to fully describe their appearances. In general, changelings can change their size within a fixed window, their volumes staying approximately the same, but the forms of their bodies changing as they please. For example, the same changeling might be able to take the form of a tall and slender Bloodbound, or a broad-shouldered Fleshcarved. Changelings can easily shed some of their volume, evaporating into a steamy gas and allowing them to shrink as tiny as they want. In order to regain that lost mass, however, they need to ingest it from food or drink again. Most of the mass they ingest directly turns into bodily volume, and as they digest, the mass is slowly lost again, so if one is starving, they body is literally slowly disappearing.
Even regardless of mass, there are other limits to their transformations. When their bodies are too spread out, growing too tall or too wide, the integrity of their bodies can't hold together any longer, leaving them in danger of breaking apart. What these limits are exactly vary from person to person and some even train their abilities, allowing for more transformations.
Cultures
Changelings are not welcome in most cities and communities, as lots of people harbor a general distrust against them, seeing them as duplicitous and dangerous. Becuase of these preconceptions, most changelings like to stay among their own kind, rarely leaving the few sanctuary cities they have created for themselves. The ones that do live amongst other races often have to keep their true nature a secret, picking one body and sticking to it for the rest of their lives.
Other changelings are used to live in hidden secluded areas where they are generally left to themselves without much interference. They often create communities in the mountains or deep in the jungles, where they can live off the land and have minimal contact with outsiders. The only people that regularly visit them are traders bringing news from the outside world.
Most of these cities are fairly isolated, leading to very different cultures between them. They are however, all to some extent influenced by the biggest of them, the city of Glimmervale. Located deep in the Verdant Wilds, a vast and dangerous jungle, it is almost impossible to find without a guide, and even then many people do not make the trip. Once there, however, people can find a sprawling city, built into the trees themselves and invisible from the outside. Additionally, the city itself seems to morph and shift, making it very hard for outsiders to find the entrance, let alone find their way anywhere once inside. Because of this natural security, the city is generally very welcoming to outsiders, assuming anyone taking the long way there is friendly, and even if they aren't, it is usually an easy task to dispose of them again. Following this model, most changeling cities have similar layouts, shifting and changing just like their inhabitants with many natural defences to deter unwelcomed visitors. What is very unique to Glimmervale, however, is their openness to outsiders, as the defences of the Verdant Wilds are strong enough that they do not have to worry much about many dangers from them. Other cities are not so lucky.
Among the higher gods, Changelings often worship Lyrax, the god of dreams and illusions, who is known for visiting their followers within dreams and giving them glimpses of the future. They are mainly worshipped by The Twilight Path, a farily disorganized religion, studying dreams and their connections to reality.