Cast Insult by paying {2}{R}.
Activate Heartless Hidetsugu by tapping it, dealing damage to each opponent equal to half their life total, rounded down, times 2, and dealing no damage to you due to Pariah's Shield.

Near-infinite damage

Heartless Hidetsugu

Pariah's Shield

Insult // Injury

Cast Insult by paying {2}{R}.
Cast Malignus by paying {3}{R}{R}. It'll enter with power equal to half the highest life total among your opponents, rounded up.
When Malignus enters, Champion of the Path triggers, causing Malignus to deal damage equal to its power doubled to each opponent due to Insult // Injury.

Each opponent loses the game

Infinite damage

Champion of the Path

Malignus

Cast Insult by paying {2}{R}
Activate your commander using the ability granted to it by Street Urchin by paying {1} and sacrificing another creature or artifact, dealing 2 damage to Smaug due to Insult // Injury.
Smaug triggers, creating two Treasure tokens.
Activate a Treasure by tapping and sacrificing it, adding {1}.
Repeat from step 2

Infinite artifact ETB

Infinite artifact LTB

Infinite artifact sacrifice triggers

Smaug the Impenetrable

Street Urchin

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 Insult // Injury.
Toralf triggers, dealing an amount of damage over the excess damage to the second indestructible creature due to Insult // Injury.
Toralf triggers, dealing an amount of damage over the excess damage to the first indestructible creature due to Insult // Injury.
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

Give Walking Ballista lifelink, if needed.
Cast Injury by paying {2}{R}.
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 3.

Infinite lifegain

Infinite lifegain triggers

Infinite +1/+1 counters on creatures you control

Walking Ballista

Unspeakable Symbol

Collective Inferno

Give Tephraderm indestructible, if needed.
Cast Insult by paying {2}{R}, doubling the damage sources you control deal this turn.
Cast Star of Extinction by paying {5}{R}{R}.
Hive Mind triggers, causing each opponent to copy Star of Extinction.
Resolve an opponent's Star of Extinction, destroying a land and dealing 20 damage to each creature and planeswalker.
Tephraderm's second ability triggers, dealing 40 damage to the opponent who controlled the Star of Extinction copy due to Insult.
Repeat from step 5 for each remaining Star of Extinction until each opponent loses the game.

Tephraderm

Hive Mind

Star of Extinction

Combos with "Insult // Injury"