Kamigawa is a Magic: The Gathering expert-level block inspired by Japanese myths and revolving around the battle between spirits (kami) and living beings. It consists of the expansion sets Champions of Kamigawa (October 1, 2004), Betrayers of Kamigawa (February 4, 2005), and Saviors of Kamigawa (June 3, 2005).
Champions of Kamigawa introduced changes to two common creature types. The Legend creature type was replaced with the Legendary supertype. The Wall creature type was freed from the associated rules that prevented Walls from attacking; Each Wall creature was changed to have the new Defender keyword which prevents them from attacking, allowing for a simpler use of the "wall" type creature across different creature types. For example, this allowed for the Lorwyn changelings, which have all creature types. Under the old rules, changelings would not be able to attack, through sheer result of being walls. Legend and Wall were the last creature types in Magic to have inherent rules associated with them. The set's expansion symbol is a torii, the entrance to the Shinto temple. This is especially important, as Kamigawa's original idea was summed up as "Shinto gone horribly wrong": Kami warring against their human worshippers.
Champions of Kamigawa introduced several new mechanics to the game. Some instant or sorcery spells have the Arcane subtype, which represent spells or abilities used by the kami. It does nothing by itself, but other cards may interact with it. One type of spell that can interact with Arcane spells are spells with the keyword "Splice onto Arcane", which can be "attached" to another Arcane spell for additional mana investment. The "spliced" spell remains in the player's hand able to be reused another time. The block contains a large number of Spirit creatures (representative of the kami), some of which were printed with the Soulshift keyword, which allows them to return another Spirit creature from the graveyard to its owner's hand when they perish. Other Spirits have abilities which trigger when another Spirit or an Arcane spell is played. By contrast, many samurai were printed with the Bushido ("way of the warrior") mechanic, which increases a creature's power and toughness by the Bushido number when it combats another creature. (This is usually compared to flanking, which weakens (-1/-1) the blockers of the creature). Certain creatures, nicknamed "heroes", are "flipped" (the card is turned 180 degrees) when particular conditions are met, becoming an entirely different, more powerful, and Legendary creature. It has a disproportionately high number of Legendary cards, more than 80 in total.
Betrayers of Kamigawa introduces two new mechanics to the game. The Ninjutsu mechanic allows a player to put a Ninja creature card from his or her hand into play tapped and attacking by paying a cost and returning an attacking, unblocked creature he or she controls to its owner's hand. The Offering ability allows the player to partially pay for a spell by sacrificing a creature of a certain creature type, and lets the spell be played as an instant. This ability is used on five Spirit creatures, the patron spirits of five non-human species in Kamigawa. Betrayers also features the first non-Wall creatures with defender.
Saviors of Kamigawa introduces several new mechanics to the game. Epic spells are powerful cards that prevent their controller from playing spells for the rest of the game, except for a copy of the spell again for free during each of his or her upkeeps. Channel, an ability similar to cycling that represents the fading barrier between the spirit world and reality, allows some spirits to have the ability to concentrate their physical form into a one-shot instant-effect. Sweep spells allow players to determine how powerful they want the spell to be, in exchange for returning lands of a required type to their owner's hand. Saviors expanded on the Flip theme, but with creatures that flip into legendary enchantments, symbolizing that creature's Essence, once their conditions are met. Saviors of Kamigawa also has a theme of "Wisdom" that rewards players for having seven cards (or some other high number of cards) in their hands. Saviors also features the first intentionally uncastable spell, Evermind, which has no mana cost. Its effect can only be achieved through the use of the Splice mechanic introduced in Champions of Kamigawa. However, new rules from Time Spiral now allow cards without mana costs to be cast, as long as the player can bypass paying the non-existent mana cost.