I want to share what I've learned about painting magical and fantastical light — fire, bioluminescence, magical spells, energy effects — because these sources break the usual rules of natural light in consistent ways.

Fantastical light sources are typically: high saturation (unlike natural light which is relatively desaturated), warm or strikingly colored rather than neutral white, and often multiple small sources rather than one large one.

The painting challenge: the magical light must illuminate surrounding surfaces convincingly. A blue magical spell lights nearby objects with blue light. The shadows on those objects are filled with the ambient scene light, not the spell color.

Painterly treatment: I use glow effects sparingly. A hard painted light area with a very gentle gradient into the surroundings reads as magical without needing an obvious Photoshop glow filter. The filter approach looks synthetic; the painted approach looks intentional.

The contrast boost: magical light often benefits from a slight increase in the subject's overall contrast — the lights brighter and the darks darker than natural light would produce. This heightened contrast is what gives the sense of powerful, otherworldly illumination.