Elemental HERO Thunder Giant (Quarter Century Secret Rare) (RA03-EN153) [Quarter Century Bonanza]

"Elemental HERO Sparkman" + "Elemental HERO Clayman"<br>Must be Fusion Summoned. Once per turn: You can discard 1 card, then target 1 monster on the field with original ATK less than the ATK of this card; destroy that target.