Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Boss's Chauffeur + Yahenni, Undying Partisan

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Boss's Chauffeur

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing Boss's Chauffeur.
2. When Boss's Chauffeur dies, its persist ability and second ability trigger.
3. Resolve the second trigger, creating a number of 1/1 Citizen creature tokens equal to the number of +1/+1 counters that were on Boss's Chauffeur.
4. Resolve the persist trigger, returning Boss's Chauffeur from your graveyard to the battlefield. It'll enter with a number of +1/+1 counters on it equal to the number of creatures you control minus 1 due to its replacement effect.
5. Resolve the Yahenni ability.
6. Repeat.

This loop relies on Eirdu, Carrier of Dawn / Isilu, Carrier of Twilight functioning on its back face to grant persist to your nontoken creatures, allowing Boss's Chauffeur to return from the graveyard with a -1/-1 counter whenever it dies. As you sacrifice Boss's Chauffeur to Yahenni, Undying Partisan's activated ability to grant it indestructible, the Chauffeur's own death trigger converts its accumulated +1/+1 counters into an army of 1/1 Citizen creature tokens. Because those entering tokens trigger the Chauffeur's alliance ability—and naturally fuel Eirdu // Isilu's convoke-granting front side if recast—the resulting engine continually recycles the Chauffeur while feeding a growing stack of +1/+1 counters onto Yahenni, Undying Partisan.