Can you attach a book to Library Pass and then move it to Abigail Foreman using Abigail's quick action? Read as written it seems possible but doesn't seem intended... You'd basically be able to completely ignore the Forced on Library Pass

A roundup of who can take Defensive Stance/what they get out of it:

Carolyn Fern:

Carson Sinclair:

Leo Anderson:

Marion Tavares (not on Arkhamdb yet):

Mark Harrigan:

Nathaniel Cho:

Roland Banks:

Sister Mary:

Tommy Muldoon:

Wilson Richards:

Zoey Samaras:

Amanda Sharpe:

Joe Diamond:

Vincent Lee:

"Skids" O'Toole:

Tony Morgan:

Diana Stanley:

Gloria Goldberg:

Lily Chen:

William Yorick:

Charlie Kane:

Lola Hayes:

Unsurprisingly, it looks like it works best as an emergency "I really need to pass this foot test" for combat-centric investigators, though it might bump the occasional Locked Door or Overgrowth into a success too.

I haven't seen this mentioned, but this card would work really well with Agnes Baker. Cancel out a treachery AND trigger her ability at the same time? Great combination.

This is basically a triple Ward of Protection, but costs 1 resource and 3 health more. Obviously you can have only 2 Ward of Protection in your deck, but together with Purifying Corruption you can cancel up to 5 treacheries! This is pretty much 1/3rd of all the treacheries you will draw. Adding Agnes Baker ability, you additionally deal 5 damage while doing that. Amazing stuff.

Assuming you don't recharge the card and only cancel out treacheries three times, the full price for Purifying Corruption would be 4 resources, 3 sanity and 3 damage. The health cost especially might be a bit high for our brave waitress, but you also have access to Heirloom of Hyperborea and assuming you have more soak (which you should, if you're playing Agnes), this is definitely something she can handle.

This card also pairs extremely well with two particular allies - Peter Sylvestre and Jessica Hyde, both of whom Agnes Baker wants in her deck anyway.

The only real drawback of this card would be the fairly expensive resource cost (4), which might be a bit high for her at times, as she generally tends to be short on supplies, especially if you run her with Fire Axe or Dark Horse, which some people do.

TLDR: So overall 4 exp and 4 resource cost for a card that will help trigger Agnes Baker ability and cancel out treacheries? Definitely something to consider.

Also, if by any chance you are playing with Carolyn Fern on the team (which is a quite common duo), all the drawbacks of Purifying Corruption magically disappear.

Q: Does this item's effect combine with Masks? And if so, can I use Wolf Mask on a test?
My understanding is the mask's triggered ability resolves "for this skill test" so I would be getting +1 to all skills during the skill test.
On the 2nd question - I know there is a rule that forbids commiting cards without proper icons to tests but I don't recall any restriction on using assest to boost a skill irrelevant to the test.

I am absolutely loving this card in my Parallel Roland deck. Both versions of Roland's deckbuilding can take it, and Red Tape makes it a fast play (so it only costs one action), which makes it just about the largest quantity draw in the game... and one action, two resources, and one card in return for five cards is also just profitable.