The Book of Retribution is a Lexicon that can be wielded by Zexion in Kingdom Hearts 358/2 Days. It is his signature weapon, and the only one he wields in Kingdom Hearts Re:Chain of Memories and Kingdom Hearts II Final Mix. The Book of Retribution, unsurprisingly, is a book, and Zexion is often seen reading it while lounging in the Grey Area.
It is unclear exactly what the pages of the Book of Retribution contain, but from what can be seen, it tells some sort of story and lacks a basic dictionary layout. The cover is a dark grey, embossed with three white, intertwined Nobody emblems. The back bears the outline of another Nobody logo. The spine of the book displays a Roman numeral for six, VI, along with the title "Hallucination: Another Side", superimposed over yet another Nobody symbol; in the North American and PAL games, "Hallucination" is replaced with "Ignes Fatui" (Latin for "Delusions"). Both "Hallucination" and "Delusions" allude to Zexion's attribute of "Illusion", and the "VI" on the book references Zexion's rank as the sixth member of Organization XIII.
Almost all of Zexion's weapons are lexicons—a type of book—and many are named after other types of books. "Retribution" is a synonym for "vengeance".
While the Book of Retribution is one of Zexion's stronger Lexicons, it is slightly unwieldy, as the combo finisher of his ground combo does not have the attack range that some of his other weapons do. When he is on the ground, Zexion's combo is comprised of a forward slam, twin horizontal slams, and then a forward toss of the Book of Retribution.
When Zexion is performing his aerial combo, he will smack enemies twice in a left-to-right fashion, then finishing the combo by throwing the Lexicon forward, which comes back to Zexion. Pressing will cause Zexion to perform both a forward and upper slam; the -Combo ending with a toss of the Book of Retribution, and his aerial combo's combo finisher.