Information from Rhythm of War is not allowed on the Coppermind until the book is out. See Coppermind:Spoilers for details on how you can still work on Rhythm of War content.
Larcener is an Epic of the Coven.
The following link contains major spoilers for the whole of Calamity and to lesser extent The Reckoners series as a whole. Please be very sure you have either read the book or are happy to be spoiled on some major points of the story.