Hatchery Sliver, Crookshank Kobolds, and Rukarumel, Biologist

Prerequisites

• Hatchery Sliver on the battlefield
• Crookshank Kobolds on the battlefield
• Rukarumel, Biologist on the battlefield
• Rukarumel on the battlefield with "Sliver" chosen

Steps

1. Cast Crookshank Kobolds by paying , and choosing to pay its replicate cost an arbitrarily large number of times by paying
2. Crookshank Kobolds triggers, creating a copy of it for each time its replicate cost was paid
3. Resolve all Crookshank Kobolds spells, causing the nontoken Crookshank Kobolds to enter the battlefield, and creating a token copy of it for each time its replicate cost was paid

Results

• Infinite ETB
• Infinite creature tokens