Toph, the First Metalbender + Ugin's Nexus + Meticulous Excavation + Overgrown Estate

Toph, the First Metalbender

Ugin's Nexus

Meticulous Excavation

Overgrown Estate

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 Overgrown Estate 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 Overgrown Estate ability.
6. Activate Meticulous Excavation by paying 2, returning Ugin's Nexus from the battlefield to your hand.
7. Repeat each turn.

This ingenious loop revolves around turning Ugin's Nexus into a land via Toph, the First Metalbender so it can be sacrificed to Overgrown Estate. Because Ugin's Nexus replaces going to the graveyard by exiling itself instead, it safely triggers its own extra turn clause. From there, Meticulous Excavation allows you to bounce Ugin's Nexus back to your hand for reuse, or alternatively, Toph's earthbend effect brings it right back from exile to repeat the process on demand.