Starving Venom Fusion Dragon (Quarter Century Secret Rare)

Card text

2 DARK monsters on the field, except Tokens If this card is Fusion Summoned: You can make this card gain ATK equal to 1 opponent's Special Summoned monster, until the end of this turn. Once per turn: You can target 1 Level 5 or higher monster your opponent controls; until the End Phase, this card's name becomes that monster's original name, and replace this effect with that monster's original effects. If this Fusion Summoned card is destroyed: You can destroy all your opponent's Special Summoned monsters.