Delney, Streetwise Lookout + Mox Amber + Dream Stalker + Heartless Summoning

Delney, Streetwise Lookout

Mox Amber

Dream Stalker

Heartless Summoning

How it works

1. Cast Mox Amber by paying 0.
2. Activate Mox Amber by tapping it, adding one mana.
3. Cast Dream Stalker by paying one mana.
4. When Dream Stalker enters, it triggers twice due to Delney, returning Mox Amber and Dream Stalker from the battlefield to your hand.
5. Repeat.