Polyraptor + Forerunner of the Empire

Prerequisites

You have a way to give Forerunner of the Empire indestructible. {6}{G}{G}available.

Steps

1. Give Forerunner of the Empire indestructible by any method.
2. Cast Polyraptor by paying {6}{G}{G}.
3. Polyraptor enters the battlefield, triggering Forerunner of the Empire, causing it to deal 1 damage to each creature.
4. All Polyraptor creatures trigger.
5. Resolve one Polyraptor trigger, creating one token copy of Polyraptor.
6. Repeat from step 3 any number of times.
7. End the loop by declining to deal damage with Forerunner of the Empire triggers and resolving an arbitrarily high number of Polyraptor triggers.