U-Class Magic covers Umbral, Dark, Water, Earth and their secondary magics. Hybrid magic that is made up of two U-Class magics is also classed as U-Class!
Umbral
The ability to use all Umbral Class magics and pure U-Class hybrids
Dark
Ability to control dark
Shade
Ability to control one's own shadow
Water
Ability to control water
Blood
Ability to control blood
Earth
Ability to control earth
Metal
Ability to control metal