The Sibsig Ceremony + Junk Diver + Workshop Assistant + Heartless Summoning

The Sibsig Ceremony

Junk Diver

Workshop Assistant

Heartless Summoning

How it works

1. Cast Junk Diver by paying 0.
2. Junk Diver enters and dies as a state-based action due to having 0 toughness.
3. When Junk Diver 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 Junk Diver from your graveyard to your hand.
7. Repeat.