Smaug the Impenetrable + Metalwork Colossus + Peregrin Took + Goblin Bombardment

Smaug the Impenetrable

Metalwork Colossus

Peregrin Took

Goblin Bombardment

How it works

1. Activate Goblin Bombardment by sacrificing Metalwork Colossus, dealing 1 damage to Smaug.
2. Smaug triggers, creating two artifact tokens due to Peregrin Took.
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. Repeat.

This clever loop uses Goblin Bombardment to deal 1 noncombat damage to Smaug the Impenetrable, turning its damage-to-Treasure ability into a pair of artifact tokens thanks to Peregrin Took's replacement effect. Those newly minted treasures serve as the exact sacrifice fodder Metalwork Colossus needs to pull itself out of the graveyard and back to your hand. Because the massive mana value of the noncreature artifacts you control reduces its casting cost down to zero, you can recast Metalwork Colossus for free and immediately feed it back into Goblin Bombardment to restart the cycle.