Athreos, Shroud-Veiled, Resourceful Defense, and Phyrexian Altar

Prerequisites

• Athreos, Shroud-Veiled on the battlefield
• Resourceful Defense on the battlefield
• Phyrexian Altar on the battlefield
• You control at least two creatures
• At least one creature has coin counter on it

Steps

1. Activate Phyrexian Altar by sacrificing a creature with coin counter, adding one mana of any color
2. Athreos and Resourceful Defense triggers
3. Resolve the Athreos trigger, returning that creature to the battlefield
4. Resolve the Resourceful Defense trigger, putting a coin counter on other creature you control
5. Repeat

Results

• Infinite colored mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers