Hi,
I couldn't find any previous topics about this interaction and several answers online seem to be contradicting each other. The question itself is pretty straight-forward:
I have a Doubling Season on the battlefield and my opponent attacks with a creature that has Infect or Wither. I block with a vanilla creature. Combat damage is dealt - are the -1/-1 counters from the attacking creature doubled or not?

Most of the more recent answers I found seem to indicate that they are not, because the combat damage itself is putting the -1/-1 counters on the creature, rather than an “effect” from a static ability like Wither. On the other hand, 702.79a could be interpreted in a way that the static abilities Wither/Infect are creating an effect that prevents the marking of regular damage and puts an equal amount of counters on it instead. While the latter interpretation might be the more implausible one, I found a thread that mentioned an [O] ruling in favor of it on the old WotC boards that have been taken down a while ago. Since that thread is gone now, I'm not sure about the reason behind the ruling, so I'm wondering: is the number of -1/-1 counters from Wither / Infect combat damage affected by Doubling Season?
If it is not, why does 609.1 (“An effect is something that happens in the game as a result of a spell or ability.”) not apply to Wither / Infect combat damage?

Edited Steffen Baumgart (Jan. 1, 2016 05:14:33 PM)