This thread is about the Monster Cards of been unsummonables due to the special requirement to Summon the cards. Warning: This thread is NOT about complaining about how hard the the summon can be summoned.
Note: These cards are not in particular any order!
Note: These cards are not in particular any order!
November 25, 2007 - Updated with more cards! (Thanks to you)
Arcana Knight Joker (Light)
Lv. 9 [Warrior/ Fusion/ Effect]
"Queen's Knight" + "Jack's Knight" + "King's Knight"
This card can only be Fusion Summoned with the above Fusion Material Monsters. While this card is face-up on the field, if a Spell, Trap, or Effect Monster targets this card, you may discard the same type of card to negate the effect. This effect can only be activated once per turn.
ATK: 3800 / DEF: 2500

Tip: This monster can be usable with a Warrior-Type Deck especially [Reinforcement of the Army]. Well, with [Future Fusion] it's very possible. Now that I think about.. I have no idea why this is here.
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VWXYZ-Dragon Catapult Cannon (Light)
Lv.8 [Machine/ Fusion/ Effect]
"VW-Tiger Catapult" + "XYZ-Dragon Cannon"
This card can only be Special Summoned from your Fusion Deck by removing from play the above cards on your side of the field. (You do not use "Polymerization"). Once per turn, remove from play 1 card on your opponent's side of the field. When this card attacks, you can change the battle position of the attack-target monster. (Flip Effects are not activated at this time.)
ATK: 3000 / DEF: 2800
Oh look, here comes [Neo-Spacian Grand Mole]
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Mirage Knight (Dark)
Lv.8 [Warrior/ Effect]
This card cannot be Normal Summoned or Set. This card cannot be Special Summoned except by the effect of "Dark Flare Knight". When this card battles another monster, during damage calculation increase the ATK of this card by the original ATK of the opponent's monster. During the End Phase after this card was involved in battle, remove this card from play.
ATK: 2800 / DEF: 2000
This card won't be able to play until [Dark Flare Knight] is destroyed by battle. Which can be run into [Sakurestu Armor], [Zaborg the Thunder Monarch], and other cards..
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Dragon Master Knight (Light)
Lv.12 [Dragon/ Fusion/ Effect]
"Black Luster Soldier" + "Blue-Eyes Ultimate Dragon"
This monster cannot be Special Summoned except by Fusion Summon. This card gains 500 ATK for each Dragon-Type monster on your side of the field except this card.
ATK: 5000 / DEF: 5000
Three cards needed.. 1 Ritual, 1 Fusion and 1 Polymerization, which can be a while.. In the late games you can play [Dragon's Mirror] for faster summoning.. Forgot about [King of the Swamps]..
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Gate Guardian (Dark)
Lv.11 [Warrior/ Effect]
This card cannot be Normal Summoned or Set. This card can only be Special Summoned by Tributing "Sanga of the Thunder", "Kazejin" and "Suijin".
ATK: 3750 / DEF: 3400
Looks mighty strong but requires 3 two-tribute monsters. Best to go with [UFOroid] with [Power Bond].. The reason why this is number 3 is right there in the first sentence.. even if you use those special effect monsters that consider 2 tribute, how long will they stay there?
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Perfectly Ultimate Great Moth (Earth)
Lv.8 [Insect/ Effect]
This monster cannot be Normal Summoned or Set. This card can only be Special Summoned by Tributing "Petit Moth" on the 6th of your turns after "Petit Moth" has been equipped with "Cocoon of Evolution".
ATK: 3500 / DEF: 3000
Say what? You have to wait for 6 turns until you get him? Hmm.. By now your opponent can Special Summon [Cyber Dragon] who has 2100 ATK points which can destroy [Coconn of Evolution] who has 2000 DEF points. Even if you equip with a spell card that can't be destroy by battle, do you sense Shield Crush?
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Armityle the Chaos Phantom (Dark)
Lv.12 [Fiend/ Fusion/ Effect]
"Uria, Lord of Searing Flames" + "Hamon, Lord of Striking Thunder" + "Raviel, Lord of Phantasms"
This card can only be Special Summoned from your Fusion Deck by removing from play the above cards on your side of the field. (You do not use "Polymerization" ). This card cannot be destroyed by battle. While this card is on the field, it gains 10000 ATK during your turn only.
ATK: 0 / DEF: 0
I'll be very surprised if anyone actually got to summon this card.. 3 Continuous Spell and Trap with 3 Fiend-Type monster in one deck..
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Blue-Eyes Shining Dragon (Light)
Lv.10 [Dragon/ Effect]
This card cannot be Normal Summoned or Set. This card cannot be Special Summoned except by offering 1 "Blue-Eyes Ultimate Dragon" on your side of the field as a Tribute. Increase the ATK of this card by 300 points for each Dragon-Type monster in your Graveyard. You can negate the effect of Spell, Trap, and Monster Cards that designate this card.
ATK: 3000 / DEF: 2500
4500 --& 3000 (Just for an effect that protects himself?)
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Metalzoa (Dark)
Lv.8 [Machine/ Effect]
This monster can only be Special Summoned from your Deck to your side of the field by offering "Zoa" equipped with "Metalmorph" as a Tribute.
ATK: 3000 / DEF: 2300
???
I would think that a card that requires a specific 2-trib monster, equipped with a specific card, to be sacrificed in order to summon from your Deck...and couldn't be summoned at ALL once it left your deck...would make the cut.
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Red-Eyes Black Metal Dragon (Dark)
Lv.8 [Machine/ Effect]
This card cannot be Normal Summoned or Set. This card can only be Special Summoned from the Deck by Tributing "Red-Eyes B. Dragon" equipped with "Metalmorph". Your Deck is then shuffled.
ATK: 2800 / DEF: 2400
Same applies as [Metalzoa]
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Exodia Necross (Dark)
Lv.4 [Spellcaster/ Effect]
This card cannot be Normal Summoned or Set. This card cannot be Special Summoned except by the effect of "Contract with Exodia". This card is not destroyed as a result of battle or by the effects of Spell or Trap Cards, and during each of your Standby Phases, increase the ATK of this card by 500 points. This card is destroyed when any of "Exodia the Forbidden One", "Right Arm of the Forbidden One", "Left Arm of the Forbidden One", "Right Leg of the Forbidden One" or "Left Leg of the Forbidden One" is not in your Graveyard.
ATK: 1800 / DEF: 0
This card can somewhat be playable due to the recent release of [Foolish Burial]
???
Using Exodia pieces for an instant win is better than using them to summon a monster.