The Sibsig Ceremony + Myr Retriever + Workshop Assistant + Shuri, Wakandan Inventor

The Sibsig Ceremony

Myr Retriever

Workshop Assistant

Shuri, Wakandan Inventor

How it works

1. Cast Myr Retriever by paying 0.
2. When Myr Retriever enters the battlefield, The Sibsig Ceremony triggers, destroying Myr Retriever and creating a 2/2 Zombie Druid creature token.
3. When Myr Retriever dies, it triggers, returning Workshop Assistant from your graveyard to your hand.
4. Cast Workshop Assistant by paying 0.
5. When Workshop Assistant enters the battlefield, The Sibsig Ceremony triggers, destroying Workshop Assistant and creating a 2/2 Zombie Druid creature token.
6. When Workshop Assistant dies, it triggers, returning Myr Retriever from your graveyard to your hand.
7. Repeat.