An interesting rules discussion came up in my meta last night. My opponent was playing Greyjoy and I was using Baratheon recursion. I had some key events in my discard pile that I could not use for King Robert because my opponent had Baelor out. Ok, so no problem there. Here's where things got a little tricky.

I played Mel's Favor to steal Baelor, but my opponent pointed out that he had Maester Kerwin in play. At this point, he told me that Kerwin could protect an Ironborn from things like stealth and deadly (which was news to me), and he could also protect him from Marched to the Wall. I hadn't heard any of this before, but I wasn't about to assume he was wrong because I simply was unfamiliar with the rules.

Anyways, back to the main point. He said he could kill Kerwin to stop Mel's Favor, but we didn't know what would happen. We ended up playing it that he kept Baelor, but the attachment was still on Baelor.

So here are my questions:

1. Can Kerwin protect from things like stealth, deadly, and Marched?

2. Can Kerwin protect from Mel's Favor, and if he can, what happens?

1. Kerwin can cancel passive effects like Marched (notice that he cancels the entire effect and NO ONE is discarded, not just his own character), but keywords cannot be canceled by definition (see FAQ 4.14), so he cannot stop things like stealth, deadly, etc.

2. Cancels, by definition, interrupt the initiation and resolution of an effect. Continuous effects, like the "take control" part of Mel's Favor, have no points of initiation and resolution to interrupt - they are simply "true/applicable" or not. So Kerwin CANNOT cancel Mel's Favor, and you should have taken control of Baelor.

(Another way to look at it: The attachment is essentially a terminal effect, like when something says "kill at 0." Even if you save from the "kill at 0," the character's STR is still 0, so it just dies again after the save. Same in your situation. You take control of the character while the attachment is attached. Even if you cancel the "take control" effect, the attachment is still attached, so you just take it again after the cancel.)

Can you clarify something for me? Doesn't Marched target the player? Assuming the Greyjoy player has more than a single character in play... how is it targeting a single Ironborn character as its only target? And isn't it also targeting an opponent's character?

Good catch on the outcome. I hadn't double-checked the play restrictions on Kerwin and forgot about the "only target" limitation.

However, Marched does not target players. (It does not, for example, say "choose a player"). The fact that each player chooses a different character to discard does not change the fact that the characters are the plot's chosen targets. Always look at what is being chosen, not who is doing the choosing. So, since the characters are chosen as the targets of Marched's card effect, it is still potentially cancelable by Kerwin - but in order to meet Kerwin's play restrictions, the GJ player would have to choose an Ironborn character, and all opponents would have to have no characters in play to choose as targets themselves. That would make the Ironborn character the only target of Marched, and Kerwin could cancel it.

Of course, it probably would have been better to just choose Kerwin to be discarded by Marched at that point....

Ah yes - thanks for the clarification. Makes sense to me now.