A dark art style with a primarily blue and purple color palette. It has strong art nouveau influences on its own, but if you add "art nouveau" to the prompt it tends to add more frames and symmetry. Characters often have dark eye shadow and wear black, along with lots of jewels and ornamentation.

This style reminds me of the artist Harry Clarke, but it was not trained on his artwork. You can bring out more of this influence by adding his name to the prompt.