Kate impaling herself on the sword that would have destroyed her team and using her blood to break it. Followed by her blood control when captured to kill one of the rakshasas. And finally the Curran and the rest of the shapeshifters arriving to rescue her.
In the fifth book, the takedown of the fortified military compound held by the Lighthouse Keepers by the entire magical community of Atlanta combined definitely counts.
In the first book, Kate gets fed up with the Pack's scare tactics and decides she's not taking any more crap. So she responds to the Beast Lord, a were-lion, like any common housecat.