So, for a defense hero(QoH), all special and normal attacks are colorless on even an opposite color attack hero(Lianna). But, QoH minions with hit harder on Lianna than on Magni.
If one of the attack heroes(joon) gets an elemental(red) defense buff (kasherek) or debuff (falcon), then, normal, minion and special attacks of the defense hero(QoH) of that element(red) on that attack hero are either reduced or increased respectively, irrespective of what color the attack hero(joon) is.