Metalwork Colossus + The Ooze + Atog + Bloodspore Thrinax

Metalwork Colossus

The Ooze

Atog

Bloodspore Thrinax

How it works

1. Cast Metalwork Colossus by paying 0, which enters with at least two +1/+1 counters on it due to Bloodspore Thrinax.
2. Activate Atog by sacrificing Metalwork Colossus.
3. When Metalwork Colossus dies, The Ooze triggers, creating a Mutagen token for each +1/+1 counter Metalwork Colossus had.
4. Resolve the Atog ability.
5. Activate Metalwork Colossus by sacrificing two Mutagens, returning it from your graveyard to your hand.
6. Repeat.

This loop transforms a free-casting giant into a self-sustaining engine by turning its death into an explosive surplus of resources. When you cast Metalwork Colossus for zero mana, Bloodspore Thrinax ensures it enters the battlefield already bearing the vital +1/+1 counters that fuel The Ooze's trigger upon the Colossus's demise. Feeding the Colossus to Atog sends it to the graveyard while pumping Atog, which simultaneously prompts The Ooze to generate a bounty of Mutagen tokens. You then use just two of those newly minted artifacts to satisfy the activation cost of Metalwork Colossus, returning it straight to your hand ready to be cast all over again.