Advanced format ruling
De-Fusion
Card effect (current official text)Target 1 Fusion Monster on the field; return that target to the Extra Deck, then, if all the Fusion Materials that were used for its Fusion Summon are in your GY, you can Special Summon all of them.
Current rulings for this card are maintained by Konami.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Advanced forum — sourced change requests get reviewed.