Magic crystalline cells are cells that grow in living beings that have and use magic. The more powerful the magic the stronger the cells. The longer that a being lives the more cells there will be, and the cells may extend the life of the being. Most of the time cells are distributed throughout the body, but sometimes they will deposit crystals that will grow as the cells deposit more crystal material. These magic crystals are highly sought after as they can be used as ingredients to make powerful items.
The magic crystalline cells are caused by magic viruses that may be slightly to highly infectious. Some areas have more viruses that may be spread in different ways. Sometimes a pocket in the world may contain ancient magic viruses. There are many different magic viruses that cause different types of crystalline cells. Each cell type causes a different type of magic.
Magic crystalline cells tap into the weave of magic to affect the world. This allows the user to manipulate the weave and therefore use magic.