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.
Results
Infinite artifact ETB.
Infinite artifact LTB.
Infinite artifact sacrifice triggers.
Infinite artifact tokens.
Infinite colored mana.
Infinite creature tokens.
Infinite creature ETB.
Infinite mana creatures you control can produce.
Infinite Treasure tokens.
Infinite untap of creatures.
Infinite creature LTB.
Infinite creature sacrifice triggers.
Infinite death triggers.
Reduce the toughness of creatures opponents control to 0.
Infinite +1/+1 counters on creatures you control.
Metadata
Bracket tag
ExhibitionBracket 1+
For any deck
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1 · Exhibition5 · cEDH
Bracket tags are estimated from the cards and results of each combo, as a guideline rather than a strict classification.