Athreos, Shroud-Veiled, Resourceful Defense, and Hammerhead, Maggia Boss

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Resourceful Defense on the battlefield
• Hammerhead, Maggia Boss on the battlefield

Steps

1. Activate Hammerhead by sacrificing the creature with a coin counter on it
2. When the creature dies, Athreos's second ability and Resourceful Defense's ability trigger
3. Resolve the Resourceful Defense 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 Hammerhead ability from step 1
6. Activate Hammerhead by sacrificing Resourceful Defense
7. When Resourceful Defense dies, it and Athreos's second ability trigger
8. Resolve the Resourceful Defense trigger, putting a coin counter and +1/+1 counters onto the other nontoken creature
9. Resolve the Athreos trigger, returning Resourceful Defense from your graveyard to the battlefield
10. Resolve the Hammerhead ability from step 6
11. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers