Metalwork Colossus + The Ooze + Altar of Dementia + Bioengineered Future

Metalwork Colossus

The Ooze

Altar of Dementia

Bioengineered Future

How it works

1. Cast Metalwork Colossus by paying 0, which enters with at least two +1/+1 counters on it due to Bioengineered Future.
2. Activate Altar of Dementia 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 Altar of Dementia ability.
5. Activate Metalwork Colossus by sacrificing two Mutagens, returning it from your graveyard to your hand.
6. Repeat.

This clever loop turns the massive mana value of artifacts into an infinite cycle of sacrifice and mill. With Bioengineered Future granting Metalwork Colossus extra +1/+1 counters upon entering the battlefield, its demise triggers The Ooze to harvest those counters into a pile of Mutagen tokens. You then use those very tokens as currency to fuel Metalwork Colossus's graveyard-recursion ability, feeding it right back into Altar of Dementia to mill your opponents out entirely.