Memnite + Tempered Steel + Altar of Dementia + Underworld Breach + Thassa's Oracle

Memnite

Tempered Steel

Altar of Dementia

Underworld Breach

Thassa's Oracle

How it works

1. Cast Underworld Breach.
2. Activate Altar of Dementia by sacrificing Memnite, milling yourself for three.
3. Cast Memnite by exiling three cards from your graveyard that are not Thassa's Oracle.
4. Repeat steps 2 and 3 until you have no cards in library.
5. Cast Thassa's Oracle.
6. Resolve its enter the battlefield trigger.

This clever loop turns the zero-mana cost of Memnite into an engine for infinite self-mill by feeding Altar of Dementia over and over. Underworld Breach provides the crucial recursive graveyard access, letting you continuously escape the tiny artifact creature back to the battlefield by exiling your other spent resources. Once your entire library is safely in the graveyard, you drop Thassa's Oracle to capitalize on your empty library and claim instant victory. The passive buff from Tempered Steel even sits in play, though this particular assembly uses the artifact creatures primarily as fuel for the millstone rather than for combat.