Metalwork Colossus + Warren Soultrader + Aetherflux Reservoir + Peregrin Took

Metalwork Colossus

Warren Soultrader

Aetherflux Reservoir

Peregrin Took

How it works

1. Cast Metalwork Colossus by paying 0.
2. Aetherflux Reservoir triggers, causing you to gain 1 life for each spell you've cast this turn.
3. Activate Warren Soultrader by paying 1 life and sacrificing Metalwork Colossus, creating a Food token and a Treasure token.
4. Activate Metalwork Colossus by sacrificing the Treasure and Food, returning Metalwork Colossus from your graveyard to your hand.
5. Repeat.

This loop uses Metalwork Colossus's built-in cost reduction, which makes the massive artifact free to cast as long as you control enough noncreature artifacts. Each time you cast it, Aetherflux Reservoir rewards your growing spell count with a steady climb in life total, easily buffering the health you spend to keep the engine moving. Warren Soultrader provides the necessary sacrifice outlet to bin the Colossus, which in turn triggers Peregrin Took's replacement effect to generate both a Treasure and an extra Food token. You then cash in those newly created artifacts to pay the ability cost that returns Metalwork Colossus straight back to your hand, ready to cast for zero mana all over again.