Underworld Breach + Diligent Excavator + Thassa's Oracle + Sakashima's Student

Underworld Breach

Diligent Excavator

Thassa's Oracle

Sakashima's Student

How it works

1. Cast the artifact creature from your hand by paying 0.
2. Diligent Excavator and Sakashima's Student 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 uses Underworld Breach to turn your graveyard into a second hand, allowing you to repeatedly cast a zero-mana artifact creature for its escape cost while exiling expendable cards to fuel the engine. As you cast that repeatable spell, Diligent Excavator acts as your milling mill-engine, constantly churning your library into your graveyard to feed Underworld Breach's exile requirement. Sakashima's Student can join the fray or copy key utility, but the true endgame relies on Thassa's Oracle: once your library has been completely milled away into nothingness, you cast it to easily meet the devotion threshold and instantly claim victory.