Marath, Will of the Wild, Mana Echoes, and Cathars' Crusade

Prerequisites

• Marath, Will of the Wild on the battlefield
• Mana Echoes on the battlefield
• Cathars' Crusade on the battlefield
• Marath has at least two +1/+1 counters on it
• available

Steps

1. Activate Marath by paying and removing a +1/+1 counter from it, creating a 1/1 Elemental creture token
2. The Elemental enters the battlefield, triggering Mana Echoes and Cathars' Crusade
3. Resolve the Mana Echoes trigger, adding for each Elemental you control
4. Resolve the Cathars' Crusade trigger, putting a +1/+1 counter on each creature you control
5. Repeat

Results

• Infinite colorless mana
• Infinite creature tokens
• Infinite ETB
• Infinite +1/+1 counters