Betrayers of Kamigawa is the name of the Magic: The Gathering expansion set which came out in January of 2005. It contains 165 cards. The set's story is inspired by Japanese medieval myths and revolves around the battle between spirits (kami) and living beings. Most of the cards have Japanese-flavored names. The set's expansion symbol is shuriken, or ninja throwing star.

Mechanics

Betrayers of Kamigawa introduces several new mechanics to the game.

• Ninjutsu allows you to put a creature card from your hand into play tapped and attacking by paying a ninjutsu cost and returning an attacking, unblocked creature to its owner's hand. Thematically, the original creature is always the Ninja, it was simply disguised. Some also interpret the flavor to be the ninja using the original creature as a distraction.
• Offering allows you to partially pay for a spell by sacrificing a creature of a certain creature type.
• Five new flip cards - Whenever you play a spirit or arcane spell, they get a ki counter. If they have two or more at end of turn, they flip and become legendary spirits that use the ki counters to activate an ability.
• New costs for Splice onto Arcane - Splice onto Arcane abilities now have nonmana costs. Also, one card, Minamo's Meddling, counters a spell and whatever is spliced onto it is discarded.

Betrayers also features the first non-Wall creatures with defender.