Incubation Druid + Cloudstone Curio + Rancor + Nature's Chosen

Incubation Druid

Cloudstone Curio

Rancor

Nature's Chosen

How it works

1. Activate Incubation Druid by tapping it, adding .
2. Activate Nature's Chosen by paying 0, untapping Incubation Druid.
3. Cast Rancor by paying , attaching it to Incubation Druid.
4. Rancor enters the battlefield, triggering Cloudstone Curio, returning Nature's Chosen from the battlefield to your hand.
5. Cast Nature's Chosen by paying , attaching it to Incubation Druid.
6. Nature's Chosen enters the battlefield, triggering Cloudstone Curio, returning Rancor from the battlefield to your hand.
7. Repeat.