Mana Echoes, Marath, Will of the Wild, and Phyrexian Altar

Prerequisites

• Mana Echoes on the battlefield
• Marath, Will of the Wild in the command zone
• Phyrexian Altar on the battlefield
• plus enough mana to pay for commander tax, if applicable available

Steps

1. Cast Marath from the command zone by paying and commander tax, if applicable, causing it to enter the battlefield with a number of +1/+1 counters on it equal to the amount of mana spent to cast it
2. When Marath enters the battlefield, Mana Echoes triggers, adding for each Elemental and Beast on the battlefield
3. Activate Marath by paying and removing a +1/+1 counter from it, creating a 1/1 Elemental creature token
4. When the Elemental enters the battlefield, Mana Echoes triggers, adding for each Elemental on the battlefield
5. Repeat from step 3 until Marath has one +1/+1 counter on it
6. Activate Marath by paying and removing a +1/+1 counter from it
7. Marath dies as a state-based action due to having zero toughness
8. Choose to return Marath to the command zone from your graveyard
9. Resolve the Marath ability, creating a 1/1 Elemental creature token
10. When the Elemental enters the battlefield, Mana Echoes triggers, adding for each Elemental on the battlefield
11. Activate Phyrexian Altar by sacrificing three Elementals, adding
12. Repeat
13. Once you have infinite colorless mana and Elemental tokens, you may cast Marath, causing it to enter with an arbitrarily large number of +1/+1 counters, and choose Marath's other modes instead

Results

• Infinite +1/+1 counters
• Infinite colored mana
• Infinite colorless mana
• Infinite commander casts
• Infinite creature tokens
• Infinite damage
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers
• Infinite storm count