Smaug the Impenetrable + Metalwork Colossus + Blasting Station + Primal Vigor

Smaug the Impenetrable

Metalwork Colossus

Blasting Station

Primal Vigor

How it works

1. Activate Blasting Station by tapping it and sacrificing Metalwork Colossus, dealing 1 damage to Smaug.
2. Smaug triggers, creating two artifact tokens due to Primal Vigor.
3. Activate Metalwork Colossus by sacrificing the two artifact tokens, returning Metalwork Colossus from your graveyard to your hand.
4. Cast Metalwork Colossus by paying 0.
5. When Metalwork Colossus enters, Blasting Station triggers, untapping Blasting Station.
6. Repeat.

This clever loop transforms our favorite greedy dragon into an endless engine of destruction, fueled entirely by the discount on Metalwork Colossus. By sacrificing the Colossus to Blasting Station, we ping Smaug the Impenetrable for 1 damage; thanks to Smaug's triggered ability, this deals noncombat damage that spawns a single Treasure, which is immediately doubled into two Treasures by Primal Vigor's replacement effect. Those two freshly minted artifacts let us instantly buy back Metalwork Colossus from the graveyard to our hand, and because its mana value reduces its cost to zero, we can cast it for free. Each time the Colossus re-enters the battlefield, Blasting Station untaps itself via its own triggered ability, allowing us to repeat the whole sequence indefinitely.