Metalwork Colossus + The Ooze + Umbral Collar Zealot + Arwen, Weaver of Hope

Metalwork Colossus

The Ooze

Umbral Collar Zealot

Arwen, Weaver of Hope

How it works

1. Cast Metalwork Colossus by paying 0, which enters with at least two +1/+1 counters on it due to Arwen.
2. Activate Umbral Collar Zealot 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 Umbral Collar Zealot ability.
5. Activate Metalwork Colossus by sacrificing two Mutagens, returning it from your graveyard to your hand.
6. Repeat.

This intricate engine leverages Arwen, Weaver of Hope to supercharge Metalwork Colossus as it enters the battlefield with a hefty cluster of +1/+1 counters, heavily reducing its casting cost to zero. When you sacrifice the Colossus to Umbral Collar Zealot, The Ooze springs into action, weaponizing those departing counters to churn out a flood of Mutagen tokens. You can then cash in two of those very same Mutagen tokens to activate Metalwork Colossus's recursion ability, returning it straight to your hand so the whole loop can begin anew.