Activate your commander using the ability granted to it by Street Urchin by paying {1} and sacrificing another creature or artifact, dealing 3 damage to Smaug due to The Flame of Keld.
Smaug triggers, creating three Treasure tokens.
Activate a Treasure by tapping and sacrificing it, adding {1}.
Repeat.

Infinite artifact ETB

Infinite artifact LTB

Infinite artifact sacrifice triggers

Infinite Treasure tokens

Infinite artifact tokens

Infinite colored mana

Infinite damage

Smaug the Impenetrable

Street Urchin

The Flame of Keld

Activate Deathless Angel twice by paying {W}{W}{W}{W}, giving two creatures an opponent controls indestructible until end of turn.
Deal noncombat damage to one of the indestructible creatures, dealing an increased amount of damage instead due to The Flame of Keld.
Toralf triggers, dealing an amount of damage over the excess damage to the second indestructible creature due to The Flame of Keld.
Toralf triggers, dealing an amount of damage over the excess damage to the first indestructible creature due to The Flame of Keld.
Repeat from step 3 an arbitrarily large number of times.
Resolve a Toralf trigger, dealing infinite damage to any target.

Infinite damage to one opponent

Toralf, God of Fury // Toralf's Hammer

Deathless Angel

At the beginning of your precombat main phase, The Flame of Keld triggers, putting a lore counter on it and increasing the amount of damage red sources you control deal by 2 this turn.
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 2 damage to any target.
Repeat from step 2 as desired.

Infinite +1/+1 counters on creatures you control

Vigor

Deathbringer Thoctar

Combos with "The Flame of Keld"