Underworld Breach + Diligent Excavator + Thassa's Oracle + Phyrexian Metamorph

Underworld Breach

Diligent Excavator

Thassa's Oracle

Phyrexian Metamorph

How it works

1. Cast the artifact creature from your hand by paying 0.
2. Diligent Excavator and Phyrexian Metamorph trigger, causing you to mill four cards.
3. The artifact creature enters the battlefield and dies as a state-based action due to having zero toughness.
4. Cast the artifact creature from your graveyard for its escape cost by paying 0 and exiling any three cards from your graveyard, except Thassa's Oracle if it is in your graveyard.
5. Repeat from step 2 until you have an empty library.
6. If Thassa's Oracle is in your hand, cast it by paying .
7. Otherwise, cast Thassa's Oracle from your graveyard for its escape cost by paying and exiling three cards from your graveyard.
8. Thassa's Oracle enters the battlefield, causing you to win the game.

This ingenious loop turns your graveyard into an endless engine by leveraging Underworld Breach, which gives every nonland card in your graveyard escape. By continuously casting and re-casting Phyrexian Metamorph as a zero-mana artifact creature that immediately dies to state-based actions, you fuel Diligent Excavator's triggered ability to mill your entire library into the graveyard. Once your library is emptied, you simply escape or cast Thassa's Oracle, whose enter-the-battlefield trigger immediately wins you the game since your devotion to blue easily exceeds your zero-card library.