Thunder Dragon Colossus (Quarter Century Secret Rare) (RA03-EN036) - Quarter Century Bonanza 1st Edition Number_SOI-EN025 you can send this card

you can send this card to the Graveyard to inflict 1000 damage to your opponent for each of your Standby Phases that have passed since this card was activated

or 1 card that specifically lists "Dark Fusion" in its text

ATK / DEF2200 / 1800

ATK / DEF2600 / 1500

the tribute must be DARK

Thunder Dragon Colossus (Quarter Century Secret Rare) (RA03-EN036) - Quarter Century Bonanza 1st Edition Number_SOI-EN025 you can send this cardTypeThunder Fusion Effect Monster AttributeDARK Level Rank8 ATK DEF2600 2400 Card Text"Thunder Dragon" + 1 Thunder monster Must be either Fusion Summoned, or Special Summoned during the turn a Thunder monster's effect was activated in the hand, by Tributing 1 Thunder Effect non Fusion Monster (in which case you do not use "Polymerization"). Cards cannot be added from the Main Deck to your opponent's hand except by drawing them. If this card would be