Boros Dwarves is a low-curve equipment aggro deck full of small creatures like Dwarven Mauler and Kili the Resourceful, so Day of Black Sun sweeps their board cheaply while our own bigger threats survive at low X. The second M.O.D.O.K. gives Designed Only for Killing, shrinking their entire team by -1/-1, which is often lethal to their small creatures while we gain life off its lifelink attacks. Winternight Stories and an Archenemy's Charm come out since we need efficient plays, not card selection, against this aggressive curve.