Xyz Summon
An Xyz (pronounced Ex-Ceed) Summon is when two or more monsters (except Tokens) of the same level "overlay" over each other to Xyz Summon a monster. An Xyz monster has a Rank (not a Level) that is equal to the level of the individual monster(s) used to Summon it (A Rank 4 monster is summoned by using Level 4 Monsters). The Rank stars start from the left and go to the right, unlike levels that go from right to left (an example of this below).
To perform a normal Xyz Summon, you need to control 2 or more face-up monsters of the same level. Then, you stack them on top of each other (or "overlay" them) and place the Xyz monster from your Extra Deck on top of the stack. No special monsters are needed to perform an Xyz summon; however, there are a few Xyz monsters that require a monsters of a certain Type or Attribute (Ex. Blade Armor Ninja, Soul of Silvermountain, Shadow of the Six Samurai - Shien). Any monster with Levels can be used to Xyz Summon a monster. There are rare cases when you can use an Xyz monster as Xyz Material monsters instead of using its regular Xyz requirements (Ex. Gaia Charger, the Thunder Charger, Number C39: Utopia Ray).
Here is an example of an Xyz Summon:
Turn Player A controls a face-up Galaxy Eyes Photon Dragon (Level 8) and 2 Photon Kaiser (Level 8). He places two Photon Kaiser cards on top of the Galaxy Eyes Photon Dragon to Xyz Summon Neo-Galaxy Eyes Photon Dragon (Rank 8).
Here is an example of an Xyz Summon:
Turn Player A controls a face-up Galaxy Eyes Photon Dragon (Level 8) and 2 Photon Kaiser (Level 8). He places two Photon Kaiser cards on top of the Galaxy Eyes Photon Dragon to Xyz Summon Neo-Galaxy Eyes Photon Dragon (Rank 8).
What happens to those monsters when they are used to Xyz Summon a monster? They become "Xyz Materials" and no longer count as "monsters" but rather like "counters" in that they serve as a way keeping track of how many resources you have to activate the effect. Most Xyz monsters can activate effects by "detaching" Xyz materials from that card (normally, you detach 1 material, but monsters like Number 91: Thunder Spark Dragon and Evolzar Laggia have you detach more than 1). To detach an Xyz material, you take one of the Xyz materials and send it to the Graveyard; it does not matter which card you send to the Graveyard.
Rules concerning Xyz Summoning and Xyz Monsters:
1.) Tokens CANNOT be used for an Xyz Summon.
2.) All monsters you wish to use for an Xyz Summon must be face-up and the same level.