Arix Sword of Feast and Famine

[Kappu1]

Does the sword trigger when damaging a planeswalker and also does it still trigger if the damage is prevented? Lots of arguments at FNM over something I thought was simple.

[Arix]

No, in both cases.

[Kenji]

For the first part, you can derive the answer from the simple fact that a planeswalker isn't a player, and is never treated as such.

For the second part of your question, let's refer to the Comprehensive Rules:

119.8. If a source would deal 0 damage, it does not deal damage at all. That means abilities that trigger on damage being dealt won't trigger. It also means that replacement effects that would increase the damage dealt by that source, or would have that source deal that damage to a different object or player, have no event to replace, so they have no effect.

Given the above, 0 damage is treated as no damage at all, and thus will not trigger Sword of Feast and Famine.