Montesi Books is written as so:
A character holding a spell book may use the following attack once per turn.
Is once per turn for the character or the book itself? Wound Ninjas be able to use the book, KO themselves and hand off the book to Elektra / DD and during the parents activation within the same turn, would the parents be able to use the book also ? Or did the book get used for the turn already?
Similarly with Corvus and Proxima or Crossbones and Sin, if they are holding one book and they mission objective and double activate, would each character be able use the same book during the same turn?
Lastly Corvus and Proxima / Sin and Bones with 2 different books double activate, can they each use their separate books they are each holding during the same turn?