Activate Sling-Gang Lieutenant by sacrificing Putrid Goblin
When Putrid Goblin dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
When Putrid Goblin enters, The Great Henge triggers, putting a +1/+1 counter on Putrid Goblin and causing you to draw a card.
Resolve the Sling-Gang Lieutenant ability.
Repeat.
This loop turns a humble goblin skeleton crew into a relentless, life-draining engine by exploiting the interaction between persist and counter-cancellation. When you sacrifice Putrid Goblin to Sling-Gang Lieutenant, it returns to the battlefield with a -1/-1 counter, but The Great Henge immediately steps in to place a +1/+1 counter on it—which, according to the rules of Magic, annihilates the -1/-1 counter entirely. This clean slate lets Putrid Goblin persist all over again every time it hits the graveyard, while The Great Henge rewards each recursion by drawing you a card and Sling-Gang Lieutenant drains your opponents to dust.