Gem-Knight Master Diamond (HA07-EN059) [Hidden Arsenal 7: Knight of Stars]

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 and original effect become the same as that banished monster's.