Athreos, Shroud-Veiled, Yahenni, Undying Partisan, and Host of the Hereafter

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Yahenni, Undying Partisan on the battlefield
• Host of the Hereafter on the battlefield

Steps

1. Activate Yahenni by sacrificing the creature with a coin counter on it
2. When the creature dies, Athreos's second ability and Host of the Hereafter's ability trigger
3. Resolve the Host of the Hereafter trigger, putting a coin counter onto itself as well as +1/+1 counters if those were present
4. Resolve the Athreos trigger, returning the creature from your graveyard to the battlefield
5. Resolve the Yahenni ability from step 1
6. Activate Yahenni by sacrificing Host of the Hereafter
7. When Host of the Hereafter dies, it and Athreos's second ability trigger
8. Resolve the Host of the Hereafter trigger, putting a coin counter and +1/+1 counters onto the other nontoken creature
9. Resolve the Athreos trigger, returning Host of the Hereafter from your graveyard to the battlefield
10. Resolve the Yahenni ability from step 6
11. Repeat

Results

• Infinite +1/+1 counters on creatures you control
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers