Sage of Hours + Extruder + Myr Battlesphere + Muldrotha, the Gravetide

Sage of Hours

Extruder

Myr Battlesphere

Muldrotha, the Gravetide

How it works

1. Cast Myr Battlesphere from your graveyard by paying 7.
2. When Myr Battlesphere enters, it triggers, creating four 1/1 Myr artifact creature tokens.
3. Activate Extruder five times by sacrificing Myr Battlesphere and the four Myr tokens, putting five +1/+1 counters on Sage of Hours.
4. Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
5. Repeat each turn.

This loop transforms Muldrotha, the Gravetide into an engine for an infinite-turn lock by repeatedly pulling key pieces from the graveyard. You cast Myr Battlesphere from the graveyard to instantly flood the board with four 1/1 Myr artifact creature tokens, providing the exact fodder needed for Extruder's sacrifice ability. By feeding both the Battlesphere and its tokens into Extruder, you effortlessly pile five +1/+1 counters onto Sage of Hours. Finally, you cash in those counters using the Sage's activated ability to secure infinite extra turns, letting you repeat the entire process indefinitely.