Xyz monster that summons itself by “eating” other monsters Xyz Material

[rock715]

Overlay leech

Rank 0

1000/2000

DARK Insect/xyz/effect

2 xyz monsters of the same rank

(This card’s rank is treated as 1 normally). You can also xyz summon this card by removing xyz materials from xyz monsters you control (attach those material to this card). This card’s rank is equal to the number of xyz material(s) used to summon this card. Once per turn, you can detach 1 xyz material from this card; reveal 1 xyz monster from your extra deck that is 1 rank higher than this card; xyz summon that monster (ignoring it's summoning condition) using this card as material (all xyz materials attach to this card become that monsters xyz materials). Once per duel: If this card is detached from an xyz monster; special summon 1 xyz monster from your GY, and if you do, attach this card to that monster as xyz material.