Hexwood

A novel by Diana Wynne Jones. A powerful magical artifact from the center of the galaxy, buried on Earth, becomes active and distorts reality in its neighborhood.

Tropes include:

""This wood," Yam told him, "is like human memory. It does not need to take events in their correct order.""
 * All Just a Dream:
 * Affably Evil: Reigner One.
 * Anachronic Order: The second mini-chapter takes place near what is chronologically the end of the book.  To be fair, there's an in-story reason for that.
 * To be precise, the chapters really occur in chronological order, but the Bannus is


 * Arthurian Legend:
 * The Baroness: Reigner Three.
 * Big Screwed-Up Family: Ironically enough, the only two major characters who probably aren't -- Reigners Three and Four -- are sister and brother.
 * The Chessmaster:
 * Chronic Backstabbing Disorder: Once  kicks into action, the Reigners are too busy trying to wipe each other out to wonder what's really going on.
 * Decoy Protagonist
 * Five-Bad Band: The Reigners
 * Gambit Roulette:


 * Mind Screw: When we say distorts reality, we mean it.
 * Well, what do you expect when you've got a  Reality Warper involved? Figurative warping of reality?
 * One-Winged Angel:
 * Smug Snake: Reigner Four.
 * Tomato in The Mirror:
 * Training From Hell: Boy howdy.
 * Fate Worse Than Death: What happens to the mothers of the Reigners' Servants.
 * When He Smiles: Mordion
 * Worthless Yellow Rocks: Flint, from Earth, is valuable elsewhere in the universe.