Activate Shilgengar by sacrificing Optimus Prime, Hero.
When Optimus Prime, Hero dies, its second ability triggers, returning it from your graveyard to the battlefield as Optimus Prime, Autobot Leader.
Activate Shilgengar by sacrificing Optimus Prime, Autobot Leader.
When Optimus Prime, Autobot Leader dies, Luminous Broodmoth triggers, returning Optimus Prime from your graveyard to the battlefield as Optimus Prime, Hero with a flying counter on it.
Resolve both Shilgengar abilities from steps 1 and 3
Repeat.
This clever loop relies on the constant, cyclical rebirth of Optimus Prime, Hero by continually leveraging its dual-faced nature between its robot and Vehicle modes. Because Optimus enters the battlefield as a fresh object each time, Luminous Broodmoth steps in to catch it when its Autobot Leader side dies, returning it to the battlefield as the Hero without needing the moth's help on the flip side. Meanwhile, Shilgengar, Sire of Famine fuels this endless cycle by treating Optimus as a sacrifical engine piece, turning every iteration into a cascade of sacrifice and death triggers while churning out a wealth of Blood tokens.