Crystalline Crawler + Sunbond + Deadeye Navigator + Gray Merchant of Asphodel

Crystalline Crawler

Sunbond

Deadeye Navigator

Gray Merchant of Asphodel

How it works

1. Activate Gray Merchant of Asphodel by paying 1, blinking it.
2. When Gray Merchant of Asphodel enters the battlefield, it and Deadeye Navigator's soulbond ability trigger.
3. Resolve the Deadeye Navigator trigger, pairing it and Gray Merchant of Asphodel.
4. Resolve the Gray Merchant of Asphodel trigger, causing each opponent to lose life equal to your devotion to black, and causing you to gain that much life.
5. Crystalline Crawler triggers, putting at least two +1/+1 counters on itself.
6. Activate Crystalline Crawler's first ability twice by removing two +1/+1 counters from it, adding 1.
7. Repeat.
8. If your devotion to black is at least three, this combo nets infinite +1/+1 counters on Crystalline Crawler and infinite mana.

This loop relies on a clever synergy of life-draining and counter manipulation to generate infinite resources, provided your devotion to black is at least three. Deadeye Navigator acts as the engine, using its soulbond ability to repeatedly blink Gray Merchant of Asphodel whenever you pay the activation cost. Every time the Merchant re-enters the battlefield, its devotion-based trigger drains your opponents and hands you a burst of life. That sudden influx of life triggers the Sunbond enchantment attached to Crystalline Crawler, showering the Crawler with fresh +1/+1 counters. From there, Crystalline Crawler converts those counters back into mana to pay for the next Deadeye Navigator blink, leaving extra counters behind to grow your mana pool and power infinitely.