Early on, Harry comes across a group of Red Court vampires in his office building—after delivering the above line, he incinerates one, and rounds the corner to face the other. The vampire takes one look at Harry, Screams Like a Little Girl and runs for its life.
Made more awesome in hindsight: The vampire that screamed and ran was apparently Esteban, one of the Red Court's most efficient and effective assassins.
Not so much a traditional Crowning Moment so much as an event so huge in-universe that it can't really be considered anything else - the complete and utter destruction of the Red Court by Harry at the end of Changes.
The final battle counts for Murphy! She killed a Physical God with one hit— after cutting her way through a crowd of vampires and elite half-vamps to get to him!
False gods! Pretenders! Usurpers of truth! Destroyers of faith, of families, of lives, of children! For your crimes against the Mayans, against the peoples of the world, now will you answer! Your time has come! Face judgment Almighty!
Murphy isn't really the one saying that — she comments later that something else was speaking through her. Considering the circumstances, that line above is probably a Pre Ass Kicking One Liner directly from a freaking Archangel.
Lea basically calls out that it was The Archangel Micheal who was spouting off. The combat was all Murphy though.
Fidelacchius bleached her clothes and Bob was circling around her head to protect her from the Lords of the Outer Night's psychic assault. So she looked likewas an avenging archangel in holy white, with a glowing golden halo, laying waste with frigging Kusanagi, The Sword of the Gathering Clouds of Heaven.
Foreshadowing: You know, exactly like she looks whenever Harry looks at her with the Sight?
Even better when you read back and notice the foreshadowing: When Harry arrives to find his crew waiting to go, she's playing chess with someone. What move is she noted as making when Harry walks into the room? Moving a Knight into a horde of enemy pieces.
And she raised Fidelacchius, let out a scream that had startled a great many large men working out at her dojo, and plunged into the warriors of the Red Court like a swimmer breasting a wave.
"You are far from the centres of your power here, demon."
"I live with a wizard. I cheat."
Harry's duel with Arianna, culminating when he beats her using a combo of his own raw powers and the fact that Arianna has never been forced to fight with just magic (resulting in her trying the same trick twice, giving Harry the chance to nail her). After Harry overpowers her, Arianna just stares up and dumbly refers to him as cattle. Harry responds first by saying "Moo" then by saying "No one messes with my little girl" before blowing Arianna's head off. Arianna is older than human language.
The final confrontation is a hundred and more pages of "Holy shit!" moments piled on top of one another. Harry gravity-pounding a Red Court horde. Harry calling out the Red King. Harry killing Arianna with a combination of Winter Knight freeze-power and forzare. Murphy and Sanya becoming Back-to-Back Badasses, with Harry, Mouse, Molly, and Thomas on support. Lea summoning the Big Damn Grey Council, which includes fucking Odin himself, who then summons an army of kenku. Ebenezar proving again why he's the Blackstaff by killing two hundred men with a gesture of the Blackstaff itself. Murphy cutting through a Lord of the Outer Night like he's not even there. Susan holding off the entire remaining Lords of Outer Night and the Red King with the Sword of Love, aka Excalibur. Martin's insane Xanatos Speed Chess to take out the Red Court at any cost.Everything. No exceptions.
What especially stands out is Harry grabbing the Red King's sword arm mid thrust, impaling, than setting his eyes on fire, before freezing his right forearm and breaking it off. DAMN
Nicely foreshadowed, too, by the fact that Harry'd come very close to putting out the White King's eyes in Blood Rites, and had set a murdering ghoul rapist's nerves and body fat ablaze in White Knight. Essentially, the Red King suffered everything Harry's dished out to his most-loathed previous enemies, but worse.
Harry pulls some insane new tricks in this one. Notable examples: Freezing a would-be hitman's gun. Tapping into an earth ley-line to crush hundreds of mooks against the floor with gravity. Using tiny fireballs to "bomb" cars as a distraction. Tripping up an onrushing monster by chucking another monster under its feet, so it slips on the resulting puddle of trampled guts. Draining the heat from a target and using that heat to power a fireball, then shattering the vamp-sicle. Lots and lots of White Magic-laced silver fire. Borrowing Luccio's tactics and slicing a monster in half with a magical laser cutter. Intentionally causing a cave-in over both him and his opponent, then opening a dimensional portal directly above himself. And then there's Molly and her "One Woman Rave," complete with Thomas break-dancing while decapitating bad guys with a sword and shooting them with a machine gun.
A couple of vampires have thrown a Molotov cocktail at Harry's apartment building, and the whole place is burning down. He managed to haul his elderly landlady out of bed to safety, but the upstairs neighbors are also old and unable to make it out on their own. Harry tries to rescue them, but can't due to a badly-timed explosion knocking him off the ladder. The old lady yells "Oh God in Heaven, help us!"... and he does. Best-timed entrance ever, Sanya.
This scene even contains something of an awesome moment for Mrs. Spunkelcrief (the aforementioned landlady). When Harry's taken out of action, she pulls the ladder upright and tries to climb it herself, and is only stopped when her bad leg collapses under her. It doesn't sound like much, but consider that she's probably in her mid-seventies, with a bum hip, and has trouble walking even with the aid of a cane under the best of circumstances. One gets the feeling that Mrs. S may have been a bit of a Determinator in her youth.
The woman also sleeps with a pistol and considers an army of ghouls pounding on her door as not worth waking up for. Although you don't live under the same roof as Harry Dresden for ten years without learning to sleep through a little thing like that.
Odin showing Harry why it's a bad idea to fuck with physical gods.
Odin unhesitatingly giving Harry exactly what he asked for, with no price tag attached, proving that some supernatural entities are neither evil nor dicks.
Not so surprising if you consider the code of honour of the ancient Norse. Courage even in the face of certain defeat is a defining characteristic for Harry, and one Odin certainly appreciates. One thinks he would love to have Harry in his band of warriors when the time to fight and lose to the Ice Giants has come. To Odin, Harry is definitely one of the good guys, so why not help him as much as he can?
Vadderung is rather insistent that Harry have some coffee and a doughnut. Since he likely realizes that Harry is on a suicide mission, Father Odin does the modern equivalent of having Harry drink Odin's Mead, giving our hero one more way back from death, as an Einherjar.
Martin gets one which was, appropriately, almost impossible to notice. In fact, no-one would ever have known he was anything but The Mole if Harry's soulgaze hadn't revealed his Thanatos Gambit to wipe out the entire Red Court while he lay dying.
Harry managing to impress the Erlking again, this time through some Politeness Judo. When he and Susan, escaping some Red Court vampires, drop in on his domain, he semi-sarcastically calls them his "guests," which Harry uses to claimSacred Hospitality.
The best part is that the rest of the goblins present are angry at what they think is a misuse of the rules of hospitality, but the Erlking thinks it is clever, equating Harry to a wily fox.
Something of a Chekhov's Gun also, as his previous encounter with Lea at his apartment established that letting one's guests win a semantic argument for courtesy's sake is a very old fae tradition. Naturally the Erlking was obliged to be gracious about it, once he had acknowledged Harry's status as a guest.
When Harry meets with Mab to accept the Winter Mantle, she gloats that he has no other options...but he interrupts her by listing his options, from least evil to most evil, all the way from accepting her offer up to activating the Darkhallow, consuming the raw lifeforce of the entire city and becoming a necromantic god.
Which he would actually do if it meant saving Maggie.
And not-so-subtly threatens Mab in the process, which takes a pretty large set in itself.
Leanansidhe kept a relatively low profile, but besides summoning the Grey Council she:
infiltrates Red King's posse of Lords of Outer Night (using a very high level veil)
takes on seven Lords of Outer Night at the same time, killing two with the first blow, and has massive fun doing it too (as usual)
"aggressively negotiates" with Odin for a direct portal to Chicago for Harry and Maggie, since "she is given to understand the little ones are quite fragile"
And she finally gets to turn Harry into a dog, which she's wanted to do for years.
Not to mention the reveal that all these years, she's been defending Harry's apartment from the Nevernever side with a flower garden so lethal, it's surrounded by mounds of bones from enemies who've tried to sneak-attack him. And Harry never even suspected it.
Villainous example for the Red King and The Lords of Outer Night. Especially when they show the power to paralyze a enemy with sheer force of will. Granted, they were defeated, but those guys still were the epitome of a A God Am I and Authority Equals Asskicking.