Moxite Refinery + Magistrate's Scepter + Mossborn Hydra + Boros Garrison

Moxite Refinery

Magistrate's Scepter

Mossborn Hydra

Boros Garrison

How it works

1. Play Boros Garrison. When it enters, it and Mossborn Hydra trigger.
2. Resolve the Boros Garrison 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 elegant loop centers on the explosive growth provided by Mossborn Hydra, whose landfall trigger doubles its +1/+1 counters every time you replay Boros Garrison to bounce itself back to your hand. You then tap Moxite Refinery to strip those accumulated counters away, feeding them directly into Magistrate's Scepter as charge counters. Finally, you cash in those charge counters to take infinite extra turns, locking your opponents out of the game entirely.