Athreos, Shroud-Veiled, Enduring Bondwarden, and Phyrexian Altar

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Enduring Bondwarden on the battlefield
• Phyrexian Altar on the battlefield
• You control at least one other nontoken creature
• Enduring Bondwarden has at least one coin counter on it

Steps

1. Activate Phyrexian Altar by sacrificing Enduring Bondwarden, adding one mana of any color
2. When Enduring Bondwarden dies, it and Athreos' third ability trigger
3. Resolve the Enduring Bondwarden trigger, putting all counters from it onto another nontoken creature you control
4. Resolve the Athreos trigger, returning Enduring Bondwarden from your graveyard to the battlefield
5. When Enduring Bondwarden enters the battlefield, its backup ability triggers, putting a +1/+1 counter on the creature who had a coin counter placed on it, and giving it the printed ability until end of turn
6. Activate Phyrexian Altar by sacrificing the nontoken creature with a coin counter on it, adding one mana of any color
7. When the creature dies, it and Athreos' third ability trigger
8. Resolve the creature's trigger, putting all counters from it onto Enduring Bondwarden
9. Resolve the Athreos trigger, returning the creature from your graveyard to the battlefield
10. Repeat

Results

• Infinite +1/+1 counters on target creature you control
• Infinite colored mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers