Elemental Hero Electrum

"Elemental HERO Avian" + "Elemental HERO Burstinatrix" + "Elemental HERO Clayman" + "Elemental HERO Bubbleman" Must be Fusion Summoned and cannot be Special Summoned by other ways. While face-up on the field, this card is also WIND, WATER, FIRE, and EARTH-Attribute. When this card is Fusion Summoned: Shuffle all banished cards into the Deck(s). This card gains 300 ATK for each monster your opponent controls that shares an Attribute with this card.