The World of Mirrodin II: Darksteel and the Fifth Dawn
The Magic Market Index Amonkhet Set Review
The Magic Market Index for April 21, 2017
Prevent all damage that would be dealt to you and planeswalkers you control this turn by sources you don't control. If damage from a creature source is prevented this way, Comeuppance deals that much damage to that creature. If damage from a noncreature source is prevented this way, Comeuppance deals that much damage to the source's controller.
11/7/2014 Comeuppance’s effect is not a redirection effect. If it prevents damage, Comeuppance (not the original source) deals damage to the creature or player as part of that prevention effect. Comeuppance is the source of the new damage, so the characteristics of the original source (such as its color, or whether it had lifelink or deathtouch) don’t affect the new damage. The new damage is not combat damage, even if the prevented damage was.
11/7/2014 If Comeuppance would deal damage to an opponent, you may redirect that damage to a planeswalker that player controls.