Elemental Hero Thunder Giant [EHC2-EN004] Secret Rare

"Elemental HERO Sparkman" + "Elemental HERO Clayman" This monster cannot be Special Summoned except by Fusion Summoned. Once per turn, during your Main Phase, by discarding 1 card from your hand, select and destroy 1 face-up monster on the field with an original ATK that is less than the ATK of this card.