Credence hates when Graves hurts Newt, so he does something about it, he uses the Obscurial against Graves, he protects Newt. He feels the anger of Graves' betrayal, feels the fear that he has of his adoptive mother, of himself. He feels everything and feeds it to the Obscurus.
OR
A different version of the subway scene in Fantastic Beasts and Where To Find Them. One where Credence isn't hurt by MACUSA.
