Workhorse + Sunbond + Emiel the Blessed + Gray Merchant of Asphodel

Workhorse

Sunbond

Emiel the Blessed

Gray Merchant of Asphodel

How it works

1. Activate Emiel the Blessed by paying 3, blinking Gray Merchant of Asphodel.
2. When Gray Merchant of Asphodel enters the battlefield, it triggers, causing each opponent to lose life equal to your devotion to black, and causing you to gain that much life.
3. Workhorse triggers, putting at least three +1/+1 counters on itself.
4. Activate Workhorse three times by removing three +1/+1 counters from it, adding CCC.
5. Repeat.
6. If your devotion to black is at least four, this combo nets infinite +1/+1 counters on Workhorse and colorless mana.

This loop relies on an engine of constant rebirth and life manipulation, where Emiel the Blessed acts as the blink-master that repeatedly resets Gray Merchant of Asphodel to drain your opponents and pile up life. As the life pours in, Sunbond ensures that your creatures grow exponentially with every tick of lifegain, synergizing directly with Emiel's own entry trigger to stack up the stats. Meanwhile, Workhorse serves as the ultimate battery, sacrificing its accumulated +1/+1 counters to generate the colorless mana needed to fund Emiel the Blessed's ability over and over again. As long as your devotion to black is high enough to sustain the loop's mana and life requirements, this quartet creates an unstoppable cascade of infinite life, mana, and triggered abilities.