I created these two enchantments as black mirrors to the white Spheres of Protection from Odyssey. While they still ensure that damage results in less life swing, they do it black's way -- by hitting the opponent back.
Sphere of Decay


Enchantment
Whenever a green source deals damage to you, that source's controller loses 2 life.
Sphere of Tyranny


Enchantment
Whenever a white source deals damage to you, that source's controller loses 2 life.