Brilliant Fusion (CORE-EN056) [Clash of Rebellions]

When this card is activated: Fusion Summon 1 "Gem-Knight" Fusion Monster from your Extra Deck, using monsters from your Deck as Fusion Materials, but change its ATK and DEF to 0. When this card leaves the field, destroy that monster. Once per turn: You can discard 1 Spell Card; the monster Special Summoned by this card's effect gains ATK and DEF equal to its original ATK and DEF, until the end of your opponent's turn. You can only activate 1 "Brilliant Fusion" per turn.