Gem-Knight Ruby [DT05-EN034] Ultra Rare

"Gem-Knight Garnet" + 1 "Gem-Knight" monster This monster can only be Special Summon by Fusion Summoned (from the Extra Deck) using the above cards as Fusion Material Monsters. Once per turn: You can Tribute 1 face-up "Gem-" monster to have this card gains ATK equal to the Tributed monster's ATK, until the End Phase. During battle between this attaching card and a Defense Position monster whose DEF is lower than the ATK of this card, inflict the difference as Battle Damage to your opponent.