Gem-Knight Master Diamond (Quarter Century Secret Rare) - Quarter Century Stampede - RA04-EN178

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.