Bloody Transformation

You sacrifice your own blood to become to gain terrifying combat power. You may roll any number of your hit dice and expend them. You then gain temporary hp equal to the total amount rolled on the expended hit dice. While you have these temporary hit points, your AC is 1 higher. In addition, once while this spell is active, you can deal an extra 3d8 necrotic damage with a melee attack. This spell ends automatically when you run out of the temporary hit points given by it.