The Ruthless Lady's Guide to Wizardry

Dellaria Wells - petty con artist, occasional thief, and partly educated fire witch - is behind on her rent. To make ends meet, Delly talks her way into a guard job in the city of Leiscourt, joining a team of unconventional women to protect an aristocrat from unseen assassins.
It looks like easy money and a chance to romance her confident companion Winn - but when did anything in Delly's life go to plan? With the help of a necromancer, a shapeshifting schoolgirl and a reanimated mouse named Buttons, Delly and Winn find themselves facing an adversary who wields a twisted magic and has friends in the highest of places.
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"Delly Wells is the best kind of protagonist. Selfish, skittish, anxious and overwhelmed, smart, opportunistic, a good heart under all the bluster, and yes, ruthless. Waggoner's characters absolutely shine...Agatha Christie in design and Pratchett-esque in execution."
Tor.com