Myr Propagator + Krark-Clan Ironworks + Lightning Greaves + Primal Vigor

Myr Propagator

Krark-Clan Ironworks

Lightning Greaves

Primal Vigor

How it works

1. Activate Lightning Greaves' equip ability by paying 0, attaching it to Myr Propagator.
2. Activate Myr Propagator by paying 3 and tapping it, creating two token copies of itself.
3. Activate Krark-Clan Ironworks twice by sacrificing the tapped Myr Propagator and a Myr Propagator token, adding CCCC.
4. Repeat.
5. Once you have infinite mana, you may forego sacrificing the Myr Propagator tokens.

This explosive loop starts by leveraging Lightning Greaves to give Myr Propagator haste for a cost of zero, allowing it to tap immediately. When you activate Myr Propagator, Primal Vigor doubles the resulting creature tokens, ensuring your population boom yields more value than you put in. You then feed those assets to Krark-Clan Ironworks, sacrificing the original and a token to generate four colorless mana—more than enough to pay the {3} activation cost to start the cycle all over again.