Fain, the Broker, Chatterfang, Squirrel General, Intruder Alarm, and Cathars' Crusade

Prerequisites

• Fain, the Broker on the battlefield
• Chatterfang, Squirrel General on the battlefield
• Intruder Alarm on the battlefield
• Cathars' Crusade on the battlefield
• Fain does not have summoning sickness

Steps

1. Activate Fain's second ability by tapping it and removing a counter from a creature you control, creating a Treasure artifact token and a 1/1 Squirrel creature token
2. When the Squirrel enters the battlefield, Intruder Alarm and Cathars' Crusade trigger
3. Resolve the Intruder Alarm trigger, untapping all creatures
4. Resolve the Cathars' Crusade trigger, putting a +1/+1 counter on each creature you control
5. Repeat
6. Once you have infinite Treasure and Squirrel tokens, you may activate Fain's other abilities

Results

• Infinite +1/+1 counters
• Infinite colored mana
• Infinite creature tokens
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite Treasure tokens
• Infinite untap of all creatures