Deathrender + Myr Retriever + Scrap Trawler + Grinding Station

Deathrender

Myr Retriever

Scrap Trawler

Grinding Station

How it works

1. Activate Grinding Station by tapping it and sacrificing Myr Retriever.
2. Myr Retriever dies, triggering itself and Deathrender.
3. Resolve the Myr Retriever trigger, returning Scrap Trawler from your graveyard to your hand.
4. Resolve the Deathrender trigger, putting Scrap Trawler from your hand onto the battlefield, and attaching Deathrender to it.
5. Scrap Trawler enters the battlefield, triggering Grinding Station, untapping Grinding Station.
6. Resolve the Grinding Station ability from step 1, causing target player to mill three cards.
7. Activate Grinding Station by tapping it and sacrificing Scrap Trawler.
8. Scrap Trawler dies, triggering itself and Deathrender.
9. Resolve the Scrap Trawler trigger, returning Myr Retriever from your graveyard to your hand.
10. Resolve the Deathrender trigger, putting Myr Retriever from your hand onto the battlefield, and attaching Deathrender to it.
11. Myr Retriever enters the battlefield, triggering Grinding Station, untapping Grinding Station.
12. Resolve the Grinding Station ability from step 7, causing target player to mill three cards.
13. Repeat.