Fabrication Module + Herd Baloth + Aetherstorm Roc

Fabrication Module

Herd Baloth

Aetherstorm Roc

How it works

1. Cast Herd Baloth by paying its mana cost.
2. When Herd Baloth enters, Aetherstorm Roc triggers, causing you to get E.
3. Fabrication Module triggers, putting a +1/+1 counter on Herd Baloth
4. Herd Baloth triggers, creating a creature token.
5. When the creature token enters, Aetherstorm Roc triggers, causing you to get E.
6. Repeat from step 3.