Moxite Refinery + Magistrate's Scepter + Mossborn Hydra + Azorius Chancery

Moxite Refinery

Magistrate's Scepter

Mossborn Hydra

Azorius Chancery

How it works

1. Play Azorius Chancery. When it enters, it and Mossborn Hydra trigger.
2. Resolve the Azorius Chancery trigger, returning it from the battlefield to your hand.
3. Resolve the Mossborn Hydra trigger, doubling the number of +1/+1 counters on it.
4. Activate Moxite Refinery by paying 2, tapping it and removing three +1/+1 counters from Mossborn Hydra, putting three charge counters on Magistrate's Scepter.
5. 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.
6. Repeat each turn.

This loop harnesses the bounce mechanic of Azorius Chancery to repeatedly trigger Mossborn Hydra, growing its +1/+1 counter count exponentially with every land drop. Moxite Refinery acts as the crucial conversion engine, stripping those rapidly accumulating counters from Mossborn Hydra to stock up Magistrate's Scepter. Once the scepter is properly fueled, you simply cash in those charge counters for endless extra turns, locking your opponents out of the game entirely.