Fan Casting Raven Darkhölme in X-Men: First Class

She is a blue skinned mutant with shapeshifting powers. She has secretly been in contact with Magneto for a while and it's him that makes Mystique go after Boliver Trask after it's revealed that he wants to create robots to exterminate mutants from existence. Erik makes his true intentions know in the end and he ends up publicly siding with Mystique.