Adagia, Windswept Bastion + Ugin's Nexus + Meticulous Excavation

Adagia, Windswept Bastion

Ugin's Nexus

Meticulous Excavation

How it works

1. Cast Ugin's Nexus by paying 5.
2. Activate Adagia by paying 3 and tapping it, creating a token copy of Ugin's Nexus.
3. Put the Ugin's Nexus token into exile due to the legend rule and its replacement effect, causing you to take an extra turn after this one.
4. Activate Meticulous Excavation by paying 2, returning Ugin's Nexus from the battlefield to your hand.
5. Repeat each turn.