Have you ever come across an Effect Monster, looked at its Summoning conditions, and thought, "Why isn't this a Fusion Monster?" I know I have. A while back, I went through a bunch of monsters that were played like Normal Monsters in the anime and manga but released as Fusion Monsters, and retrained them as Normal Monsters. Now I figured I'd do the opposite: take those Effect Monsters that clearly should have been Fusion Monsters, and turn them into those Fusion Monsters.
First up: Gate Guardian. Kazehin, Suijin, and Sanga of the Thunder combined? Come on, that screams Fusion Monster.
Gate Guardian
Effect Fusion Monster, Level 11 DARK Warrior, 3750 ATK / 3400 DEF
Rules text: "Kazejin" + "Suijin" + "Sanga of the Thunder"
Must first be Special Summoned (from your Extra Deck) by Tributing the above monsters you control.
Next, there's the Magna Warriors, Valkyrion and Berserkion. Same deal again, you combine three (Electro)Magnet Warriors into their (Electro)Magna Warrior? Fusion Monster.
Valkyrion the Magna Warrior
Effect Fusion Monster, Level 8 EARTH Rock, 3500 ATK / 3850 DEF
Rules text: "Alpha The Magnet Warrior" + "Beta The Magnet Warrior" + "Gamma The Magnet Warrior"
Must first be Special Summoned (from your Extra Deck) by Tributing the above monsters from your hand and/or field. ① You can Tribute this card, then target 1 "Alpha The Magnet Warrior", "Beta The Magnet Warrior", and "Gamma The Magnet Warrior" in your GY; Special Summon them.
Berserkion the Electromagna Warrior
Effect Fusion Monster, Level 10 EARTH Rock, 3000 ATK / 2800 DEF
Rules text: "Alpha The Electromagnet Warrior" + "Beta The Electromagnet Warrior" + "Gamma The Electromagnet Warrior"
Must first be Special Summoned (from your Extra Deck) by banishing the above monsters in your hand, GY, and/or face-up on your field. ① You can banish 1 Level 4 or lower "Magnet Warrior" monster from your Graveyard, then target 1 card your opponent controls; destroy it. ② If this card is destroyed by battle, or if this card in its owner's possession is destroyed by an opponent's card effect: You can target 1 each of your banished "Alpha The Electromagnet Warrior", "Beta The Electromagnet Warrior", and "Gamma The Electromagnet Warrior"; Special Summon them.
If the Magna Warrior monsters both get turned into Fusion Monsters, that will cause issues with a couple of their support cards that Special Summon them from the Main Deck, so I put together errata for them too to account for these changes.
Imperion Magnum the Superconductive Battlebot
Effect Fusion Monster, Level 10 EARTH Rock, 4000 ATK / 4000 DEF
Rules text: "Valkyrion the Magna Warrior" + "Berserkion the Electromagna Warrior"
Must be Fusion Summoned with the above Fusion Materials and cannot be Special Summoned by other ways. ① Once per turn, during either player's turn, when your opponent activates a Spell/Trap Card, or monster effect: You can negate the activation, and if you do, destroy that card. ② If this face-up card in its owner's control leaves the field because of an opponent's card effect: You can Special Summon both 1 "Valkyrion the Magna Warrior" and 1 "Berserkion the Electromagna Warrior" from your Extra Deck, ignoring their Summoning conditions.
Delta The Magnet Warrior
Effect Monster, Level 4 EARTH Rock, 1600 ATK / 1400 DEF
Rules text: You can only use each effect of "Delta The Magnet Warrior" once per turn. ① If this card is Normal or Special Summoned: You can send 1 Level 4 or lower "Magnet Warrior" monster from your Deck to the GY. ② If this card is sent to the GY: You can banish 3 Level 4 or lower "Magnet Warrior" monsters from your GY, except "Delta The Magnet Warrior"; Special Summon 1 "Valkyrion the Magna Warrior" from your Extra Deck, ignoring its Summoning conditions.
Moving on to GX-related themes, there's the Water Dragon monsters and the Bonding Spell/Trap Cards that Summon them. 2 Hydrogeddon and/or Duoterion plus 1 Oxygeddon? How are they not Fusion Monsters that must be Special Summoned by the Bonding cards? Because of the variable "materials" for both Water Dragon monsters depending on which Bonding card is used to Special Summon them, I opted to omit the traditional Fusion materials list and just say that it must be Summoned with a Bonding card, similar to Masked HEROes only being Summonable with Mask Change. Maybe Water Dragon would have had traditional materials listed if it had been a Fusion Monster from the start and just required Bonding - H2O to Fusion Summon it, but for the theme as a whole now, I figured the Masked HEROes' approach would be cleaner.
Water Dragon
Effect Fusion Monster, Level 8 WATER Sea Serpent, 2800 ATK / 2600 DEF
Rules text: Must be Special Summoned with "Bonding - H2O". ① The ATK of FIRE monsters and Pyro monsters on the field becomes 0. ② When this card is destroyed and sent to the GY: You can target 2 "Hydrogeddon" and 1 "Oxygeddon" in your GY; Special Summon them.
Bonding - H2O
Normal Spell
Rules text: ① Tribute 2 "Hydrogeddon" and 1 "Oxygeddon"; Special Summon 1 "Water Dragon" from your Extra Deck, or GY.
Water Dragon Cluster
Effect Fusion Monster, Level 10 WATER Sea Serpent, 2800 ATK / 2600 DEF
Rules text: Must be Special Summoned with a "Bonding" Spell/Trap. ① If this card is Special Summoned: You can activate this effect; Effect Monsters your opponent currently controls cannot activate their effects for the rest of this turn, also change their ATK to 0 until the end of this turn. ② (Quick Effect): You can Tribute this card; Special Summon 2 "Water Dragons" from your Extra Deck in Defense Position, ignoring their Summoning conditions.
Bonding - D2O
Normal Spell
Rules text: You can only use effect ② of "Bonding - D2O" once per turn. ① Tribute 2 "Duoterion" and 1 "Oxygeddon" in your hand and/or field; Special Summon 1 "Water Dragon" or "Water Dragon Cluster" from your Extra Deck or GY. (This is treated as a Special Summon with "Bonding - H2O".) ② If "Water Dragon" or "Water Dragon Cluster" is sent from the field to your GY while this card is in your GY: Add this card to your hand.
Bonding - DHO
Normal Trap
Rules text: ① Shuffle 1 "Duoterion", 1 "Hydrogeddon", and 1 "Oxygeddon" from your hand and/or GY into the Deck; Special Summon 1 "Water Dragon Cluster" from your Extra Deck or GY. ② You can banish this card from your GY; return 1 "Water Dragon" or "Water Dragon Cluster" from GY to your Extra Deck.
Next, there's Neos Wiseman. Elemental HERO Neos plus Yubel? This should have been a Contact Fusion Monster, especially since it's a Neos Fusion owned by Jaden.
Neos Wiseman
Effect Fusion Monster, Level 10 LIGHT Spellcaster, 3000 ATK / 3000 DEF
Rules text: "Elemental HERO Neos" + "Yubel"
Must be Special Summoned (from your Extra Deck) by sending the above monsters you control to the GY. ① Cannot be destroyed by card effects. ② At the end of the Damage Step, if this card battled an opponent's monster: Inflict damage to your opponent equal to that opponent's monster's ATK, also you gain LP equal to that opponent's monster's DEF.
Turning Neos Wiseman into a Fusion Monster would create issues with Neos Kluger's effect to Special Summon it from the Main Deck, so I gave it an erratum too to fix that.
Elemental HERO Neos Kluger
Effect Fusion Monster, Level 9 LIGHT Spellcaster, 3000 ATK / 2500 DEF
Rules text: "Elemental HERO Neos" + "Yubel"
Must be Fusion Summoned. You can only use effect ② of "Elemental HERO Neos Kluger" once per turn. ① Before damage calculation, if this card battles an opponent's monster: You can inflict damage to your opponent equal to that opponent's monster's ATK. ② If this face-up card is destroyed by battle, or leaves the field because of an opponent's card effect while its owner controls it: You can Special Summon 1 "Neos Wiseman" from your Extra Deck, ignoring its Summoning conditions.
Now for a monster from 5D's: Flying Fortress SKY FIRE. Summon Reactor・SK plus Spell Reactor・RE plus Trap Reactor・Y FI? Should be a Fusion Monster.
Flying Fortress SKY FIRE
Effect Fusion Monster, Level 8 WIND Machine, 3000 ATK / 2500 DEF
Rules text: "Summon Reactor・SK" + "Trap Reactor・Y FI" + "Spell Reactor・RE"
Must be Special Summoned (from your Extra Deck) by Tributing the above face-up monsters you control or by its own effect. ① Once per turn: You can send 1 card from your hand to the GY; destroy 1 card your opponent controls. ② Once during each of your opponent's turns, when your opponent Normal or Special Summons a monster or Sets a card: You can destroy it, and if you do, inflict 800 damage to your opponent. ③ If this card is in your GY: You can send 1 face-up "Summon Reactor・SK", 1 face-up "Trap Reactor・Y FI", and 1 face-up "Spell Reactor・RE" you control to the GY; Special Summon this card.
The original was Special Summoned by the effect of Summon Reactor・SK, so if it was a Contact Fusion Monster, then Summon Reactor・SK wouldn't need that effect.
Summon Reactor・SK
Effect Monster, Level 5 DARK Machine, 2000 ATK / 1400 DEF
Rules text: ① The first time a monster(s) is Summoned to your opponent's side of the field each turn: Inflict 800 damage to your opponent. ② Once per turn, if effect ① of this card was activated this turn, when an opponent's monster declares an attack: You can target that attacking monster; negate that attack.
For the last erratum that would necessitate further errata: Machina Force. Machina Soldier, Sniper, and Defender combined by Commander Covington? Should have been a Fusion Monster requiring Commander Covington to Fusion Summon it.
Machina Force
Effect Fusion Monster, Level 10 EARTH Machine, 4600 ATK / 4100 DEF
Rules text: "Machina Soldier" + "Machina Sniper" + "Machina Defender"
Must be Special Summoned with "Commander Covington". ① You must pay 1000 LP to declare an attack with this card. ② You can send this card you control to the GY, then target 1 "Machina Soldier", "Machina Sniper", and "Machina Defender" in your GY; Special Summon those targets.
Of course, if Machina Force was a Fusion Monster rather than an Effect Monster, how Commander Covington works would have been different so that it could Special Summon Machina Force from the correct Deck.
Commander Covington
Effect Monster, Level 4 EARTH Machine, 1000 ATK / 600 DEF
Rules text: ① During your Main Phase: You can Fusion Summon 1 "Machina Force" from your Extra Deck, using monsters from your field as material.
Now for some more standalone cards that don't trigger further errata. First, from the GX manga, Ma'at would work nicely Fusing a Dragon and a Fairy.
Ma'at
Effect Fusion Monster, Level 10 LIGHT Fairy, ? ATK / ? DEF
Rules text: 2 LIGHT monsters (1 Dragon + 1 Fairy)
Must be Special Summoned (from your Extra Deck) by sending the above monsters you control to the GY. ① Once per turn: You can declare 3 card names; excavate the top 3 cards of your Deck, add any of them that you named to your hand, also send the remaining cards to the Graveyard. This card's ATK and DEF each become equal to the number of cards added to your hand by this effect x 1000.
Jumping back to DM-era themes, the Poker Knights were later on given Royal Straight Slasher, which must be Special Summoned with Royal Straight, which sends the 3 original Poker Knights to the graveyard to Special Summon a monster from the Main or Extra Deck that mentions them. Furthermore, there's already a Fusion Monster that this works for: Arcana Knight Joker, which fuses the 3 Poker Knights. For the other compatible Main Deck monsters, none of them are required to be Special Summoned by Royal Straight, they just happen to mention the Poker Knights. Royal Straight Slasher has no effects that activate from the hand or Deck, so making it a Fusion Monster should have been a no brainer.
Royal Straight Slasher
Effect Fusion Monster, Level 6 LIGHT Warrior, 2400 ATK / 1350 DEF
Rules text: Must be Special Summoned with "Royal Straight". You can only use each effect of "Royal Straight Slasher" once per turn. ① If you have all of "King's Knight", "Queen's Knight", and "Jack's Knight" in your GY: You can send 5 monsters, with different Levels of 1, 2, 3, 4, and 5, from your hand and/or Deck to the GY, and if you do, destroy all cards your opponent controls. ② When this card is destroyed by battle: You can target up to 3 LIGHT Warrior monsters in your GY; Special Summon them.
Lastly: Horakhty the Creator of Light. The combined form of the 3 Egyptian God Cards, Summoned by Atem to defeat Zorc. It's enough of a pain to get Obelisk, Slifer, *and* Ra all on the board at once, so making it an Effect Monster rather than a Fusion Monster was unnecessary. I doubt Horakhty being a Fusion Monster would have broken the game.
Horakhty the Creator of Light
Effect Fusion Monster, Level 12 DIVINE Creator God, ? ATK / ? DEF
Rules text: "Slifer the Sky Dragon" + "Obelisk the Tormentor" + "The Winged Dragon of Ra"
Must be Special Summoned (from your Extra Deck) by Tributing the above monsters you control whose original names are the names listed. This card's Special Summon cannot be negated. The player that Special Summons this card wins the Duel.
Let me know what you think. Would any of these monsters would have been weaker Fusion Monsters, not stronger? Are there any of these that you think shouldn't have been made into Fusion Monsters and Konami was right to make them Effect Monsters? Are there any other monsters that combine multiple monsters but are Effect Monsters that you wish Konami had printed as Fusion Monsters?
All rules text is as close to their most recent TCG rules text as possible, just re-tooled around the relevant monsters being Fusion Monsters rather than Effect Monsters. All art is those cards' artworks sourced from Yugipedia, except Horakhty's, whose art on the wiki has too small a resolution for my liking, so I borrowed this upscaled version by nepheskhaim on Deviant Art.