Solar Array + Magistrate's Scepter + Meticulous Excavation

Solar Array

Magistrate's Scepter

Meticulous Excavation

How it works

1. Activate Solar Array by tapping it, adding one mana of any color and causing the next artifact spell you cast to have sunburst.
2. Cast Magistrate's Scepter by paying 3 using three different colors of mana.
3. Magistrate's Scepter's sunburst ability triggers, causing it to enter with three charge counters on it.
4. Activate Magistrate's Scepter's second ability by tapping it and removing three charge counters from it, causing you to take an extra turn after this one.
5. Activate Meticulous Excavation by paying 1, returning Magistrate's Scepter from the battlefield to your hand.
6. Repeat each turn.

This clever loop relies on Solar Array to infuse your artifact spells with sunburst, ensuring that Magistrate's Scepter enters the battlefield already stocked with the three charge counters it needs to immediately cash them in for an extra turn. Once you take that extra turn, you use Meticulous Excavation to bounce Magistrate's Scepter right back to your hand, allowing you to replay it and repeat the cycle indefinitely.