A Fusion Substitute Monster (融合素材代用モンスター, Yūgōsozai Daiyō Monsutā) is a monster with an effect that allows it to replace a single specifically named Fusion Material Monster for the Fusion Summon of a Fusion Monster, as long as the other monster(s) used are the correct one(s).
Fusion Substitute Monsters cannot be used for:
- Fusion Monsters that can only be Special Summoned from the Extra Deck by removing the Fusion Material Monsters listed on it from your field (Contact Fusion), such as with the "Elemental HERO Neos", "Gladiator Beast", and "VWXYZ" Fusion Monsters.
- Fusion Monsters that state "Must first be Fusion Summoned with the above Fusion Material Monsters." or "Must be Fusion Summoned with the above Fusion Material Monsters and cannot be Special Summoned by other ways.", like "Gem-Knight Ruby" or "Rainbow Neos".
- Fusion Substitute Monsters cannot be used as Fusion Material Monsters for the Fusion Summon of a Fusion Monster that states "A Fusion Summon of this monster can only be done with the above Fusion Material Monsters.", but monsters in the Hex-Sealed Fusion series can be used as Fusion Material Monsters for the Special Summon of these monsters with their Ignition Effect since it is not a Fusion Summon.
- Fusion Monsters that do not specifically name any of their Fusion Material Monsters, like "Ojama Knight" or "Evil HERO Dark Gaia".
- If the Fusion Monster has both specifically named and unnamed Fusion Material Monsters (like "Ultimate Ancient Gear Golem"), then a Fusion Substitute Monster can be used, but only for the specifically named Fusion Material Monster.
- A Fusion Summon which is already using another Fusion Substitute Monster.
- A Fusion Summon with "Cyberdark Impact!", because the monsters that must be used as Fusion Materials are specifically named on the card performing the Fusion Summon.
The effect that allows Fusion Substitute Monsters to replace a Fusion Material has no classification. It applies on the field (even while face-down), in the hand, and in the Graveyard. It does not apply while in the Main Deck or while banished, so this effect cannot be used for "Future Fusion" or "Parallel World Fusion".
Fusion Substitute Monsters
Treated as alternate name
Some cards can replace Fusion Material Monsters by treating their name as that of a Fusion Material Monster.
For example, "Elemental HERO Prisma" can send a Fusion Material Monster listed on a Fusion Monster card from the Deck to the Graveyard to treat its name as that card's. Since it is being treated as that card's name and not replacing a Fusion Material Monster, it is not a Fusion Substitute Monster and treated as being correct, so can be used for the Fusion Summon of monsters with strict Fusion Materials, such as "Cyber End Dragon" and "Cyber Blader". Also, for Fusion Summons in which Fusion Substitute Monsters are valid, it can be used in the same Fusion Summon as one.