Job 40:15-24 describes Behemoth as a powerfully muscled, grass eating creature with “bones like bronze and limbs like bars of iron” that lives at the top of a mountain. The word has since come to be synonymous with “gigantic” although a specific size is never mentioned. Big and powerful, Behemoths fit solidly into green, but have been in every color except black (as it is used in the sense of “large creature” rather than a creature type).
Job 41 describes the Leviathan much more fiercely: he is a sea dwelling monster with scales so close together that no air can get between them and they “cannot be sundered.” When he sneezes he calls forth lightning, and he breathes smoke and fire. His eyes are bright enough that he illuminates the dark sea around him. He cannot be defeated by fish hook, sling, javelin, barbed irons or clubs and “when he raises himself up, the mighty are afraid.” Primarily blue, (with the exception of Simic Skyswallower and Nemesis of Reason), Magic emphasizes the large, sea dwelling aspects of leviathan rather than the more draconic fire-breathing aspect.