Cast Changeling Outcast by paying 0 due to Ragemonger.
When Changeling Outcast enters the battlefield, Sethron and Cloudstone Curio trigger.
Resolve the Cloudstone Curio trigger, choosing to return nothing to your hand.
Resolve the Sethron trigger, creating a 2/3 Minotaur creature token.
When the Minotaur token enters the battlefield, Cloudstone Curio triggers, returning Changeling Outcast to your hand from the battlefield.
Repeat.
This clever loop transforms a humble one-mana changeling into an unstoppable recruitment engine. Because Changeling Outcast possesses every creature type, it counts as a Minotaur and effortlessly benefits from Ragemonger's cost reduction to enter the battlefield completely free. As it arrives, Sethron, Hurloon General steps in to muster a fresh 2/3 red Minotaur token, while Cloudstone Curio watches the entry and triggers to bounce the original Changeling Outcast right back to your hand. You can then replay the Outcast for zero mana, letting the token it just created trigger Cloudstone Curio anew to repeat the entire cycle for an endless horde of warriors.