Unspeakable Symbol + Sage of Hours + Gray Merchant of Asphodel + Soulherder

Unspeakable Symbol

Sage of Hours

Gray Merchant of Asphodel

Soulherder

How it works

1. At the beginning of your end step, Soulherder's second ability triggers, blinking Gray Merchant of Asphodel.
2. Soulherder's first ability and Gray Merchant of Asphodel trigger.
3. Resolve the Soulherder trigger, putting a +1/+1 counter on it.
4. Resolve the Gray Merchant of Asphodel trigger, causing each opponent to lose life equal to your devotion to black, and you to gain life equal to the life lost this way.
5. Activate Unspeakable Symbol five times by paying 15 life, putting five +1/+1 counters on Sage of Hours.
6. Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.
7. Repeat each turn.

This loop leverages Soulherder's end-step blink to continuously reset Gray Merchant of Asphodel, draining the table dry while growing Soulherder with its own tracking ability. To bridge this into an overwhelming victory, Unspeakable Symbol converts your life total directly into +1/+1 counters that feed Sage of Hours. By cashing in those counters for extra turns, you ensure that Soulherder can keep blinking Gray Merchant of Asphodel turn after turn until the opponents are completely whittled away.