Activate Yawgmoth's first ability by paying 1 life and sacrificing another creature.
When the creature dies, Moonlit Wake triggers, causing you to gain 1 life.
Resolve the Yawgmoth ability, causing you to draw a card and allowing you to put a -1/-1 counter on up to one creature.
The Locust God triggers, creating a 1/1 Insect creature token with flying and haste.
Repeat.
This magnificent transmutational engine relies on the interplay between life management and token generation to keep your crucible boiling indefinitely. By feeding creatures to Yawgmoth, Thran Physician, you pay the life cost to draw cards, which immediately triggers The Locust God to spawn a fresh 1/1 Insect token ready to take its place on the altar. Meanwhile, Moonlit Wake passively cushions your health total every time a creature perishes, completely offsetting Yawgmoth's life payment and allowing you to churn through your entire library while spreading -1/-1 counters across the battlefield.