I’m very excited to see Diana Stanley being added to Arkham Horror LCG! She’s one of my favourites from the Arkham series’.

How effective do we think she will be? Personal I’m not a fan of the skills of 3 as I prefer to play as a specialist not a generalist: what does everyone else think?

In terms of her investigator ability how many cards do we currently have that cancel game effects? I can only think of Protective Ward.

She'll be interesting. I'm not sure she'll be the most powerful mystic, simply because she'll need setup before she can get a strong Willpower (she can cap out at 6 WP but Akachi comes out of the gate with 5, no questions asked), but it remains to be seen, and we don't know her deckbuilding requirements yet.

Her unique cancellation event is the most powerful in the game, and her unique asset lets her get double use out of all the cancels, so she will have massive control over the game.

As for what her ability covers - there's no strict definition of a "game effect" in the rules ("card effect" and "framework effect" are defined) but I suspect the intention is that it basically means any card that tells you to "cancel" or "ignore" something. So, Hypnotic Gaze cancels an attack, that counts. Counterspell cancels a chaos token, that counts. Dark Prophecy draws 5 chaos tokens and ignores 4 of them, that counts. Defiance ignores the effects of a chaos token, that counts (since it sets up a standing effect where the effects of the token are cancelled you could even argue it works even if the named token isn't drawn - I don't think that's intended, but I expect someone will make a rules query to that effect before too long).

Depending on her deckbuilding, there's other cancel/ignore effects available in game - for instance, I've Had Worse and Perseverance cancel damage/horror, Forewarned and Dr William T Maleson cancel encounter cards, Lucky Dice and Against All Odds ignore chaos tokens, Dodge and Infighting cancel attacks, and .45 Automatic (2) and Marksmanship ignore keywords (but that's a stretch)! The Survivor cards A Test of Will and Devil's Luck don't really work for her, as they will be exiled regardless of whether you activate her ability or not.

One thing I really love about her is that she confronts you with interesting dilemmas. Do you use Ward of Protection to cancel an encounter card that isn't much of a problem, in order to get the Willpower boost, or do you save it for something much worse later on? With her unique asset, can you afford the Willpower hit for cancelling something using a card already under her investigator? I'm a fan of everything that gives players interesting decisions to make.

Her balanced stats are OK, again it's a bit like Akachi or Father Mateo, who have quite broad statlines aside from Willpower, but it remains to be seen whether her deckbuilding will let her leverage them. Without thinking of off-class cards, I'd certainly run 2x Knife and 2x Flashlight, so I have options for contributing before I have my Willpower set up.

She has a few pretty major weaknesses. As stated above, she takes time to set up - this is already a weakness of Mystics, who need to find and play their Shrivelling or Rite of Seeking before they can properly do their jobs; Diana needs that, as well as cancel cards and the resources to play them. Her ability gives her card draw and resources when she uses it so that might help attenuate the problem, but it'll still be there. Her low Sanity (and make no mistake, 7 is low for a Mystic) is a serious issue, as Ward of Protection (which Diana might play twice as often as other mystics) hits your sanity, and her signature weakness gives you the choice of horror or losing stored cards and therefore willpower. It might be that her deckbuilding helps with this, but it'll be harder to justify Arcane Research on her.

I wonder whether she'll end up with a more esoteric deckbuilding than just 5 mystic/2 off-class (though Mystic/Guardian would be interesting), or Mystic plus keyword. All the mystics so far in game are pretty much pure mystics, even Agnes (since Survivor mainly gives her glue cards and utility cards, like Lucky! or sanity soak from Peter S), so it would be nice to move away from that for once. We might see something more akin to Carolyn Fern, with a line like "Cards that "cancel" or "ignore" effects, levels 0-5", and Diana only having access up to level 3 in her own class... Pure speculation of course, but speculation can be fun.

Assuming she can have anything with the words ignore or cancel, quite a lot actually. It depends a lot on how exactly it is phrased. Does drawing several tokens and ignoring some of them count?

With ignore:

.45 automatic (2), marksmanship: Ignore retaliate

Eat lead, against all odds, dark prophecy, groteque statue, lucky dice, Olive McBride: draw several tokens, ignore some

Defiance: choose one token before drawing, ignore that one

More for cancel:

I've had worse, Armor of Ardennes, Devil's Luck, Perseverance: ignore damage

A test of will, William T. Maleson, Forewarned, Ward of Protection: cancel a treachery card

Dodge, narrow escape, infighting, hypnotic gaze: cancel an attack

Counterspell: cancel a token

Honestly, if I was going to build her, I would mostly ignore her willpower and build a support mystic. Cancelling, healing, bag manipulation. Should be decent in multiplayer.

@Allonym what a thoughtful consideration of Diana's strengths and weaknesses. I particularly liked your observation about the tension between cancelling things with Ward of Protection to boost willpower, or holding on to those 'must cancel' targets. I suppose with a willpower of 1 to start with, there will be more nasty treacheries that other investigators might shrug off that Diana would like to cancel.

https://arkhamdb.com/find?q=x%3Acancel|ignore&sort=name&view=list&decks=player&spoilers=hide is a list of all cards with 'cancel' or 'ignore' on them. Some obviously don't fit particularly well, as @Eldan985 outlines really nicely.

Personally, I'm looking forward to seeing how much the Twilight Blade encourages replayability of events, and how much once you're at 4-6 willpower you just stick with what you're at...