Books like Malum Discordiae by Ashlyn Drewek

"Once, Max dreamed of a career, a home, a loving family. Now all she wants is freedom ... and revenge. A witch named Giselle transformed Max into a warrior with extraordinary strength, speed, and endurance. Bound by spellcraft, Max has no choice but to fight as Giselle's personal magic weapon--a Shadowblade--and she's lethally good at it. But her skills are about to be put to the test as they never have before... The ancient Guardians of the earth are preparing to unleash widespread destruction on the mortal world, and they want the witches to help them. If the witches refuse, their covens will be destroyed, including Horngate, the place Max has grudgingly come to think of as home. Max thinks she can find a way to help Horngate stand against the Guardians, but doing so will mean forging dangerous alliances--including one with a rival witch's Shadowblade, who is as drawn to Max as she is to him--and standing with the witch she despises. Max will have to choose between the old life she still dreams of and the warrior she has become, and take her place on the side of right--if she survives long enough to figure out which side that is...."--p. [4] of cover.