Toph, the First Metalbender + Ugin's Nexus + Meticulous Excavation + Bloodflow Connoisseur

Toph, the First Metalbender

Ugin's Nexus

Meticulous Excavation

Bloodflow Connoisseur

How it works

1. Cast Ugin's Nexus by paying 5.
2. At the beginning of your end step, Toph triggers, causing Ugin's Nexus to become an artifact land creature.
3. Activate Bloodflow Connoisseur by sacrificing Ugin's Nexus. Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one.
4. Toph triggers, returning Ugin's Nexus from exile to the battlefield.
5. Resolve the Bloodflow Connoisseur ability.
6. Activate Meticulous Excavation by paying 2, returning Ugin's Nexus from the battlefield to your hand.
7. Repeat each turn.

This fascinating loop transforms a seemingly innocuous artifact into a renewable engine for infinite turns, leaning heavily on type-changing magic. Toph, the First Metalbender plays the crucial foundational role by turning Ugin's Nexus into a land, allowing it to become a creature when Toph's earthbend ability targets it. Once it is a creature, Bloodflow Connoisseur can readily sacrifice it, which triggers the Nexus's replacement effect to exile itself and grant you an extra turn. Finally, Meticulous Excavation allows you to bounce the Nexus right back to your hand so you can recast it on your next turn, ensuring the sequence loops indefinitely.