Activate Makeshift Munitions by paying {1} and sacrificing another creature or artifact, dealing 2 damage to Smaug due to Sawhorn Nemesis.
Smaug triggers, creating two Treasure tokens.
Activate a Treasure by tapping and sacrificing it, adding {1}.
Repeat.

Infinite artifact ETB

Infinite artifact LTB

Infinite artifact sacrifice triggers

Smaug the Impenetrable

Makeshift Munitions

Sawhorn Nemesis

Activate Triskelion by removing a +1/+1 counter from it, putting two +1/+1 counters on it due to Vigor.
Activate Triskelion by removing a +1/+1 counter from it, dealing 1 damage to any target.
Repeat as desired.

Infinite damage

Infinite +1/+1 counters on creatures you control

Vigor

Triskelion

Give Walking Ballista lifelink, if needed.
If Walking Ballista has less than two +1/+1 counters on it, activate Unspeakable Symbol by paying 3 life, putting a +1/+1 counter on Walking Ballista.
Activate Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 4 damage to an opponent or a permanent an opponent controls, and causing you to gain 4 life.
Repeat from step 2.

Infinite lifegain

Infinite lifegain triggers

Walking Ballista

Unspeakable Symbol

Collective Inferno

Activate Anti-Venom using Walking Ballista's ability by removing a +1/+1 counter from it, targeting itself and putting two +1/+1 counters on it due to its replacement effect and Sawhorn Nemesis.
Activate Anti-Venom using Walking Ballista's ability by removing a +1/+1 counter from it, dealing 1 damage to any target.
Repeat.

Infinite +1/+1 counters on a creature

Anti-Venom, Horrifying Healer

Agatha's Soul Cauldron

Activate Deathbringer Thoctar by removing a +1/+1 counter from it, putting two +1/+1 counters on it due to Vigor.
Activate Deathbringer Thoctar by removing a +1/+1 counter from it, dealing 1 damage to any target.
Repeat as desired.

Combos with "Sawhorn Nemesis"