They're Planeswalkers from the 'Magic: The Gathering' franchise. Although they only have superficial resemblances with Ruby, Weiss, Blake, and Yang, and are the completely wrong colors for them. Example, Jace best resembles Ruby (although not that much) and he is a blue color scheme, with blue tattoos.
Very impressionistic and very nicely put together. I like how you put each of the girls' sigils with them. I particularly like the trick of just using monochrome contrast using the girls' signature colours. It really gives a very, very bold and striking feel to the entire piece. Well done!