Soul Fusion

Soul Fusion is a technique acquired by Matt Crystalus-Uchiha due to lack of his soul's dark side. When certain emotions emerge, upon contact, Matt's light soul merges with part of the other individual's soul, achieving his or her signature abilities, as well as weapons and appearance.

Origin
Soul Fusion was first performed by an ancient Crystalian due to lack of spirit power, he would touch his companions to fight the enemies with their powers until his soul would finally reconstruct itself.

Louis notes that this ancient Crystalian might have some relation with Galamon somehow.

Fusions
Lufenian Soul - Matt when absorbing Luke's power, becomes a Crystalian with Lufenian abilities. Regardless of never having any formal training in Magic, Matt with this Soul Fusion is able to use Shin-level white and black magic. His ears also get pointy, a common feature of all Lufenians. He also looks slightly older.

Quincy Soul - Matt when absorbing Takeda's power becomes a Quincy. With this soul, Matt becomes a master with bow and arrows, he is also faster than swift with his moves. Matt gets 6 Seele Schneider in golden color to reflect Galaxia, which, differently from a regular one, cuts what is physical, and not energy. His appearance consists of a white coat with a smal Quincy cross inside the Uchiha clan's emblem.