Alright, what happens here? Does the world blow up?

Wrecking Ball said:

Depends on who reveals it. (This works with Den of the Wolf, too, BTW.)

If you reveal it, your Cat loses her immunity because she is only immune to opponent's card effects.

If your opponent reveals it, it's an opponent's card effect. Your Cat is immune to it and thus ignores it.

I'm trying to figure out a good way to say this in general terms.... Perhaps an example that is easier to see is trying to put Milk of the Poppy on a "No Attachments" character. It is not legal to put the attachment on the character even though once the attachment is on the character, it would be legal to attach it. The same thing is true with an opponent's card effect trying to remove Cat's immunity. You need Wardens or Den to be applied before it is legal to apply it. It's kind of like saying the ends do not justify the means. If the starting conditions don't mesh, you can't do it - even if the ending conditions would resolve the conflict. So just like "No Attachments" trumps Milk of the Poppy, Cat's immunity trumps an opponent's Wardens of the North or Den of the Wolf.

Thank you. That was a great explanation and I completely understand it, but it still feels wrong.

Wrecking Ball said:

Yup. It feels wrong because we are so used to "adding up" all of the various effects and applying the result to the card. You know, the old "Character STR = base STR +/- all applicable modifiers" thing. Works with icons, granting and removing keywords (like immunity), etc., etc. So it feels like this, as with anything else, should be "Cat's immunity status = printed text + modifier," which would be "immune to opponent's card effects - all immunities = no immunity." That's the way it works for every other card with immunity, right? And it is the way it works when the person who controls Wardens/Den also controls Cat.

The trick, though, is that the equation is really "base + applicable modifiers." The fact that Wardens/Den is not applicable when you are "doing the calculation" (and thus should not be included) can feel very wrong since it seems like it would be applicable after it was included.

~So there. I explained it again. Just like you didn't want/need me to do.

ktom said:

That is exactly what I was thinking when I read it!

Another question about Cat o' the Canals

My opponent has King Robert's Host in play and standing, I have Cat of the Canals in play: can I initiate a Power Challenge against my opponent?

I would say no, because Cat of the Canals is immune to opponents cards, but King Robert's Host passive ability hits only players and not characters, so I think the immunity of Cat is uselless here.

Similar question if Stannis Baratheon (core set) is attacking and I have Cat in play, but no Lords: can I make Cat participate in the challenge?

Immunity only lets cards ignore effects that would be applied to them.

The effects on King Robert's Host and Stannis are not applied to characters; they are applied to players. When you read them, they tell you what an opponent cannot do. If the opponent cannot declare attackers, it doesn't matter that Cat is immune - the opponent still cannot do the declaring. Said another way, Cat's immunity does not extend to the player that controls her.

However, there are similar effects that speak directly to what can be done with characters. There is a difference between "opponent's cannot declare power challenges" and " Lord characters cannot be declared as attackers in a power challenge." The first tells you what an opponent can (or cannot) do while the second tells you what a character can (or cannot) do.

So, while Cat's immunity does not get around King Robert's Host or Stannis, it does get around something like The Fox's Teeth (she could be declared as a defender even if she wasn't kneeling - and, in fact, could not be declared as a defender when knelt because she'd be immune to that, too).