Mister Gutsy + Nim Deathmantle + Krark-Clan Ironworks + Thunderous Velocipede

Mister Gutsy

Nim Deathmantle

Krark-Clan Ironworks

Thunderous Velocipede

How it works

1. Activate Krark-Clan Ironworks by sacrificing Mister Gutsy, adding CC.
2. When Mister Gutsy dies, its second ability and Nim Deathmantle trigger.
3. Resolve the Mister Gutsy trigger, creating a number of Junk tokens equal to the number of +1/+1 counters that were on it.
4. If you created a Junk token, activate Krark-Clan Ironworks by sacrificing a Junk, adding CC.
5. Resolve the Nim Deathmantle trigger, causing you to pay 4 to return Mister Gutsy from your graveyard to the battlefield with a +1/+1 counter on it, and attaching Nim Deathmantle to it.
6. Repeat.