Hahaha! Me too!
But there is at least magic in this book, whereas no one explained how the Ocean crew managed to put the fake money bags in the vault.
But it wasn't really about the heist. That was just the framework for the story about treachery and double-crossing. If the heist was the centerpiece of the story, the title would have been "Bank Job" or something like that. "Skin Game" refers to a scam or a con. It is also the title of a movie, about an antebellum con artist who would ride into town and sell a slave for a substantial amount of money. Except the "slave" was his partner, and they'd break him out and make off with the sale price. That's pretty much what Mab did with Harry - "sold" him to Nicodemus with the express purpose of cheating the buyer. The reason for their team-up is a heist because that's another layer of deception. It's not a burglary, it's a weapon raid, it's a con, it's a revenge plot, it's a transaction disguised as a theft. Valmont foreshadows the job when she realizes that stealing Harvey's dossier was an audition, just as Harry realizes the same thing about the effort to break into the vault.
I'm operating on the assumption that she didn't want her daughter being sacrificed. She was back on Team Nick for the revenge attack on the Carpenters' house.
I loved the image at the end of Michael & Charity sitting together with their legs each propped up.

___

I doubt even Harry really thinks Lasciel is gone. Hannah, maybe. Lasciel, nah. Look at how slowly she was brought along last time. He touched the coin at the end of Death Masks. He started suspecting something was up in Blood Rites, only really putting it together when getting his hand charred revealed her sigil on his palm. He struggled with her presence in Dead Beat, only accepting the idea of using her help at the end, and then she was a problem/ally in Proven Guilty, and converted and lost in White Night.

As a master manipulator, who knows Harry inside and out, operating on the scorned lover (or more like rejected stalker) mentality, and contesting his custody of their mutual offspring, she is too good a villain to go down with this much left to go in the series. I think this is only the start of an arc with her as his arch nemesis. He's gone up against Nicodemus three times, hurting him more each time. How do you top that in a capital 'E' Evil villain?

Lasciel's role in this was only to be part of Nicodemus' surprise ploy. No other Denarian would have provided the "oh shit" factor for the reader that she does. If Butcher is the kind of author who can envision characters who set up redundant plans that take care of multiple objectives with one move, and fallback goals and opportunities for multiple wins, it's pretty safe to say that he is capable of the same sort of economy in plot twists and character deployment. Using her in this way provided drama and emphasized the danger of Nicodemus' trump card, while being true Nicodemus' plot (which of his followers would be a better choice to take out the only living man to have come as close to killing him as Harry did in their last encounter than one who had been in his head, and who would be more motivated than the Denarian whose greatest failure was embodied in that same wizard? ), and at the same time, set her up for the future, with even more dangerous host(s).

It had me worried, since both previous appearances by Nicodemus resulted in a severe hit to the Knights. With Sanya not showing up to get crippled or murdered, Michael taking up the Sword had me concerned. I suppose the breaking of Fidelacchius and his re-retirement counts.
I have a very low tolerance for nerd pandering, only recently being able to bring myself to binge through "Chuck" on Netflix, despite being a fan of both Adam Baldwin and Yvonne Strahovsky. I particularly hate when they twist things around to create a situation where a nerd's particular obsessions save the day, or when they create an all-encompassing superweapon/power that lets some loser step up and put the people who busted their humps to become badasses to shame. Butcher took that concept right to the edge of tolerability, and I liked the bit at the end where he acknowledged that he was going to need the Carpenters' training and to get in shape, because the Swords are NOT superpowers.
For an insecure and inexperienced kid, isolated obscurity can be a safer bet than exposure and rejection. Especially given how badly he wanted Lasciel's shadow, the parasite's mother, out of his head. There's also the parallel with Molly's fear of telling the Carpenters that she's the new Winter Lady. Harry had the same fear of revealing that he had Lasciel's shadow in his head but Michael was all about the acceptance and trust, allowing his friend to not say anything even at the outset of a teaching relationship with his daughter. Molly's situation is less directly oppositional to Michael's former vocation, and as his daughter, has even more reason to expect his acceptance and forgiveness than Harry did. Kids just ain't logical about how they relate to their parents.
That pissed me off, because in a recent discussion with another fan who took Daniel Carpenter's position from Ghost Story, I defended Karrin as a good choice because she was smart enough to understand what the Swords are not, and they were entrusted to Harry and later her, because they understand restraint and the limitations of power. And she made many of those points in her talk with Harry prior to meeting the team...only for it to all go right out of her little blonde head because she wuvs Harry so much she lost her temper at the guy who threatened him. That's a rookie-level mistake that Harry himself should have learned better from making it way back in book 3. Speaking of that incident, I thought that was a nice circular bit, where young Harry C brings Michael the Sword to entrust it to Harry D at the end, since it was to protect Charity in labor with little Harry that big Harry misused Amoraccius and led to it's temporary loss to a servant of Winter.

Yeah, that was the impression I got from the beginning. Cold Days ended on November 1 (say 2012 for argument's sake), and this one is in the spring, but of 2014, rather than 2013, by what Harry said. He says Demonreach has been suppressing the headaches for a year, which could mean a year since he awoke at the end of Ghost Story, but if Demonreach can't suppress the parasite in Chicago, I doubt he could have done it during the months Harry was rehabbing in Winter. So logically, it's been a year since Demonreach first suppressed it in Cold Days, on Halloween. Harry also says he's spent a year studying the island's defenses, which has to mean it's been at least a year since Cold Days. Plus, it now being spring, your estimate seems right.

Anyway, I like Demonreach, and the idea of him having this scary island on which he's perfectly comfortable, but it gives a Knight of the Cross nightmares. I can also see the point of his maintaining some sort of pied a terre in Chicago. Between his take from the heist, his resumption of Warden pay that the Gatekeeper promised, and I would hope some sort of remuneration from Winter's apparently considerable resources (if appearances are as important as suggested back when he first took the job, I would imagine that Mab and Lea would want him to have the sort of place that impresses people who come to visit, rather than him being on the other side of that impression as is usually the case), he could actually get it done. Especially given all his complaints about not having his magical supplementary devices or facilities to replace them in the last two books. He could use a place to hang with friends and have Maggie over if he really is going to be a part of her life.

Awesome! Source?
IDK. I think Harry stepping in to set things right would just be a step backward. Part of his credit is how well his friends have managed in his absence, no matter how much they grumble about the difficulties. Expand Mab's assessment of his history with Molly to parallels with his friends, like Karrin, Butters, the Alphas, the Paranet and so on. Viewed through Mab's lens, Harry showing up to kick Fomor ass and drive them out of Chicago for all and for good, would be a ratification of her perspective. We know from Harry's ideals that he was, if anything, trying to help Molly stand on her own, and set a good example, rather than what Mab claimed in Cold Days. He has succeeded if his friends are able to stand on their own and hold the line without him. He has failed, and Mab was right all along (and by extension, she's right about his inevitable fall to the lure of Winter's power), if all he has been doing this whole time was recruiting and creating a band of henchmen who are dependent on him for everything. It increases his personal power, but doesn't really do much for his protegees and friends, aside from obviate their own choices by forcing them to bind themselves more tightly to him for survival. Besides, he's moved up. He's not the small town sheriff anymore, he's a high-ranking officer in the national army, and a special agent for the Department of Homeland Security. He can't keep running out to take care of local problems when he's worried about issues on the national level. Better all round if he restricts himself to an advisory capacity to the BFS, like Lea or Rashid or other high level players were to him at earlier stages in his career.

I'll put my own ideas in a separate response.