Heritage Druid + Nettle Sentinel + Cloudstone Curio

Heritage Druid

Nettle Sentinel

Cloudstone Curio

How it works

1. Cast an Elf from your hand by paying its mana cost.
2. If the Elf was green, Nettle Sentinel triggers, untapping itself.
3. When the Elf enters the battlefield, Cloudstone Curio triggers.
4. Holding priority, activate Heritage Druid by tapping it, Nettle Sentinel and another Elf, adding .
5. Resolve the Cloudstone Curio trigger, returning Heritage Druid from the battlefield to your hand.
6. Cast Heritage Druid by paying .
7. Nettle Sentinel triggers, untapping itself.
8. When Heritage Druid enters the battlefield, Cloudstone Curio triggers, returning the Elf cast in step 1 from the battlefield to your hand.
9. Repeat.