Goat format ruling
The Dark - Hex-Sealed Fusion
Card effect (current official text)You can substitute this card for any 1 Fusion Material Monster, but the other Fusion Material Monster(s) must be correct. You can Tribute Fusion Material Monsters on the field, including this face-up card; Special Summon 1 corresponding DARK Fusion Monster from your Extra Deck.
Rulings
- When you use this monster’s second effect, you also get its first effect. So this monster enables you to perform a Special Summon of a Fusion Monster without "Polymerization", etc., and also acts as a "substitute" for one of the Fusion Material Monsters.
- Using the second effect of this monster does not "properly" Fusion Summon the Fusion Monster. So it cannot be revived from the GY, etc. If you use "Polymerization" then you can revive the Fusion Monster from the GY, even if you used this monster as a "substitute" Fusion Material Monster.
- To use the second effect of this monster, you must Tribute this monster plus the legal Fusion Material Monster (s) written on the Fusion Monster. For example, to Special Summon "B. Skull Dragon" you must Tribute "The Dark – Hex-Sealed Fusion" as well as either "Red-Eyes B. Dragon" or "Summoned Skull".
- This monster’s second effect cannot be used to Special Summon Fusion Monsters that can only be Summoned by Fusion Summon, such as "Dark Paladin".
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Goat forum — sourced change requests get reviewed.