Maja, Bretagard Protector + Ashaya, Soul of the Wild + Cloudstone Curio + Memnite

Maja, Bretagard Protector

Ashaya, Soul of the Wild

Cloudstone Curio

Memnite

How it works

1. Cast Memnite by paying 0.
2. When Memnite enters the battlefield as a Forest land due to Ashaya, Maja triggers, creating a 1/1 Human Warrior creature token.
3. When the Human Warrior enters the battlefield, Cloudstone Curio triggers, returning Memnite to your hand from the battlefield.
4. Repeat.

This looping engine comes together brilliantly by turning your creature spells into a self-sustaining loop of landfall and enter-the-battlefield triggers. Thanks to Ashaya, Soul of the Wild, your nontoken creatures are also Forest lands in addition to their other types, which allows you to cast a free artifact creature like Memnite and immediately have it count as a land entering the battlefield. That land entry triggers Maja, Bretagard Protector to create a 1/1 white Human Warrior creature token, which in turn causes Cloudstone Curio to trigger because a nonartifact permanent has entered. Because the Warrior token shares the creature type with Memnite (or rather, Cloudstone Curio simply cares that another permanent shares a permanent type with the entering permanent), you can use the Curio's ability to bounce Memnite right back to your hand, ready to be recast for zero mana and repeat the cycle indefinitely.