Chaos Xyz Change is a form of Xyz Summoning first seen in episode 18 of the ZEXAL anime and the first variation of the standard Xyz Summon. It requires a "Number" Xyz Monster to perform. Only "Chaos Numbers" monsters can be Summoned through this method. The original Xyz Monster and its Xyz Materials becomes the Chaos Numbers' Xyz Materials.
In the TCG/OCG, this style of Xyz Summon is not applied, instead, the only Xyz Monster so far that can be Summoned through this method simply allows its basic "Number" form to be used as Xyz Material.
So far the only known monster Summoned through this method is "Chaos Number 39: Utopia Ray" and "Sacred Ptolemys M7".
How to Chaos Xyz Change
The required "Numbers" card +
The remaining Xyz Materials on the "Numbers" card =
A "Chaos Numbers" card with 1~3 Xyz Materials.