Athreos, Shroud-Veiled, Umbral Collar Zealot, and Resourceful Defense

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Umbral Collar Zealot on the battlefield
• Resourceful Defense on the battlefield

Steps

1. Activate Umbral Collar Zealot by sacrificing the creature with a coin counter on it
2. When the creature dies, Resourceful Defense and Athreos trigger
3. Resolve the Resourceful Defense trigger, putting a coin counter on another nontoken creature you control
4. Resolve the Athreos trigger, returning the creature that died in step 1 from your graveyard to the battlefield
5. Resolve the Umbral Collar Zealot ability
6. Repeat
7. Activate Umbral Collar Zealot by sacrificing the creature with a coin counter on it
8. When the creature dies, Athreos's second ability and Resourceful Defense's ability trigger
9. Resolve the Resourceful Defense trigger, putting a coin counter onto itself as well as +1/+1 counters if those were present
10. Resolve the Athreos trigger, returning the creature from your graveyard to the battlefield
11. Resolve the Umbral Collar Zealot ability from step 1
12. Activate Umbral Collar Zealot by sacrificing Resourceful Defense
13. When Resourceful Defense dies, it and Athreos's second ability trigger
14. Resolve the Resourceful Defense trigger, putting a coin counter and +1/+1 counters onto the other nontoken creature
15. Resolve the Athreos trigger, returning Resourceful Defense from your graveyard to the battlefield
16. Resolve the Umbral Collar Zealot ability from step 6
17. Repeat

Results

• Infinite creature LTB
• Infinite creature ETB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite surveil