Advanced format ruling
Future Fusion
Card effect (current official text)During your 1st Standby Phase after this card's activation: Show 1 Fusion Monster in your Extra Deck and send the Fusion Materials listed on it from your Main Deck to the GY. During your 2nd Standby Phase after this card's activation: Fusion Summon 1 Fusion Monster from your Extra Deck with the same name as the monster you showed, and target it with this card. When this card leaves the field, destroy that target. When that target is destroyed, destroy this card.
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.