Moxite Refinery + Magistrate's Scepter + Mossborn Hydra + Orzhov Basilica

Moxite Refinery

Magistrate's Scepter

Mossborn Hydra

Orzhov Basilica

How it works

1. Play Orzhov Basilica. When it enters, it and Mossborn Hydra trigger.
2. Resolve the Orzhov Basilica 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.

By repeatedly bouncing and replaying Orzhov Basilica, you trigger Mossborn Hydra's landfall ability to exponentially grow its +1/+1 counters each turn. Moxite Refinery then harvests those abundant counters to easily charge up Magistrate's Scepter without paying its steep mana cost. This fuels an endless chain of extra turns, completely locking your opponents out of the game while your ever-expanding hydra stands ready to finish them off.