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 that enters with at least two +1/+1 counters on it due to Master Biomancer.
The Squirrel enters the battlefield, triggering Intruder Alarm, untapping all creatures.
Repeat.
Once you have infinite Treasure and Squirrel tokens, you may activate Fain's other abilities.