3 "Gem-Knight" monsters Must first be Fusion Summoned. This card gains 100 ATK for each "Gem-" monster in your Graveyard. Once per turn: You can banish 1 Level 7 or lower "Gem-Knight" Fusion Monster from your Graveyard; until the End Phase, this card's name becomes that monster's, and replace this effect with that monster's original effects.
Banishes 1 level 7 or lower “Gem-Knight” Fusion monster from your Graveyard to allow this card to gain the banished monster’s effect. This effect is optional.
Must use 3 “Gem-Knight” monsters for a Fusion summon.
Its effect can be challenging to use since it requires “Gem-beast” Fusion monsters in the graveyard.
You can utilize any 1 of the Gem-Knight Fusion Monsters effect depending on situation, since you can only put a maximum of 5 cards in Extra Deck.
Gem-Knight Fusion Monsters
Gem-Knight Master Diamond can use any one of these Fusion monster’s effect as though the effect is its own, if it banishes that Fusion monster from the Graveyard. Gem-Knight Prismaura’s effect allows you to destroy 1 face-up card on the field by discarding 1 “Gem-Knight” monster from your hand to the Graveyard. Gem-Knight Seraphinite’s effect allows you to perform an additional Normal Summon/Set 1 monster for that turn. Gem-Knight Ruby’s effect allows you to tribute 1 “Gem-Knight” monster on the field to gain ATK equal to the tributed monster’s ATK until the End Phase. Additionally, if Gem-Knight Master Diamond attacks a defense position monster, inflict piercing damage to your opponent. Gem-Knight Topaz’s effect allows you to attack twice during your Battle Phase, and at the same time, if it destroys an opponent’s monster, inflict damage equal to that destroyed monster’s ATK to your opponent. Gem-Knight Citrine’s effect will prevent your opponent from activating cards or card effects when Gem-Knight Master Diamond attacks, or is being attacked, until the End Phase.
Since you are most likely to perform a considerable amount of Fusion summons to get to use Gem-Knight Master Diamond’s effect, you can use these cards to support your Fusion actions. Fusion Recycling Plant can recycle 1 fusion material monster to your hand, and also search for Polymerization from your deck. King of the Swamp can be treated as 1 fusion material required for Fusion Summon, and at the same time it also can be used to search 1 Polymerization from your Deck. Fusion Sage can search 1 Polymerization from your deck.
Master of Fusion Can be used each time your Life Points decrase by 1800. In the Draw Phase, instead of doing a normal draw, one Polymerization Spell Card, from outside of your Deck, is added to your hand.
the thing is, you can use a fusion gem knight as the materiel for diamond. so open with ruby or topaz, then fuse with two others. ruby or topaz is in your grave yard, and diamand has plenty in the grave to boost attack. not saying its easy. i just think thats the best way to go about it.