Time Sieve + Mycosynth Lattice + Rionya, Fire Dancer + Abhorrent Overlord

Time Sieve

Mycosynth Lattice

Rionya, Fire Dancer

Abhorrent Overlord

How it works

1. At the beginning of your combat phase, Rionya triggers, creating at least one token copy of Abhorrent Overlord with haste.
2. When the Abhorrent Overlord token enters the battlefield, it triggers, creating at least four 1/1 Harpy creature tokens.
3. Activate Time Sieve by tapping it, sacrificing the Abhorrent Overlord token and the Harpy tokens, causing you to take an extra turn after this one.
4. Repeat each turn.

The magic of this loop begins with Mycosynth Lattice, which turns every permanent on the battlefield into an artifact, paving the way for everything else. With the board so transformed, Rionya, Fire Dancer can target Abhorrent Overlord at the start of combat, creating a hasty token copy that immediately swells your ranks with Harpy tokens thanks to its devotion-triggered ability. Because Mycosynth Lattice has made all of those fresh tokens into artifacts, you have exactly the five sacrifices needed to fuel Time Sieve and seize an extra turn. Repeat this process on each successive turn, and you will lock your opponents out of the game entirely with an endless string of combat steps and infinite turns.