The Sibsig Ceremony + Myr Retriever + Junk Diver + Enthusiastic Mechanaut

The Sibsig Ceremony

Myr Retriever

Junk Diver

Enthusiastic Mechanaut

How it works

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