Harry Potter and the Forgiven Ones

After Voldemort fell, Dumbledore and Moody knew they were still out there. Dark wizards who stalked the shadows with cloak and dagger. In a time of peace, they recruited and trained three gifted magus to sever the hands that held those daggers. They would be the ones to tip the scales should Voldemort ever return. Permitted use of the Unforgivable Curses, they are "The Forgiven".