When Crimson Kobolds enters the battlefield, Samwise Gamgee's first ability and Cloudstone Curio trigger.
Resolve the Cloudstone Curio trigger, returning nothing to your hand.
Resolve the Samwise Gamgee trigger, creating a 2/2 Cat creature token with haste due to Jinnie Fay.
When the Cat enters the battlefield, Cloudstone Curio triggers, returning Crimson Kobolds from the battlefield to your hand.
Repeat.
This clever engine revolves around a zero-mana catalyst: casting Crimson Kobolds for free triggers both Samwise Gamgee and Cloudstone Curio simultaneously. As Samwise creates a Food token, Jinnie Fay, Jetmir's Second steps in to gracefully convert that Food into a hasty 2/2 Cat token instead. That Cat's arrival satisfies Cloudstone Curio's nonartifact permanent condition, allowing you to bounce the original Crimson Kobolds right back to your hand so you can recast it all over again.