Cast Devastating Onslaught by paying {10}{R}, creating five token copies of Terror the Peaks.
The Terror of the Peaks tokenss enter the battlefield, triggering the nontoken Terror of the Peaks five times, and each Terror of the Peaks token four times.
Resolve all Terror of the Peaks triggers, dealing 125 damage divided among a maximum of 25 targets.

Near-infinite damage

Devastating Onslaught

Terror of the Peaks

Cast Devastating Onslaught by paying {2}{R}, targeting an artifact or creature you control.
Holding priority, cast Dualcaster Mage by paying {1}{R}{R}.
When Dualcaster Mage enters the battlefield, it triggers, copying Devastating Onslaught, targeting Dualcaster Mage.
Resolve the copy of Devastating Onslaught, creating a token copy of Dualcaster Mage.
Repeat from step 3.

Infinite ETB

Infinite creature tokens with haste

Infinite magecraft triggers

Dualcaster Mage

Cast Devastating Onslaught by paying {6}{R}, creating six token copies of Exalted Sunborn.
Whenever you create one or more tokens until the beginning of your end step, you will instead create 128 times as many of those tokens due to the Exalted Sunborns.

Near-infinite token doubling

Exalted Sunborn

Cast Mana Geyser by paying {3}{R}{R}, adding {R} for each tapped land your opponents control.
Cast Devastating Onslaught by paying {4}{R}, creating two token copies of Pinnacle Monk with haste.
When the Pinnacle Monk tokens enter, they trigger, returning Mana Geyser and Devastating Onslaught from your graveyard to your hand.
Repeat.

Infinite LTB

Infinite sacrifice triggers

Infinite death triggers

Infinite storm count

Infinite red mana

Mana Geyser

Pinnacle Monk // Mystic Peak

Cast Devastating Onslaught by paying {6}{R}, creating three token copies of Biovisionary with haste.
At the beginning of your end step, each Biovisionary triggers from their own abilities, and each Biovisionary token triggers from the ability given to it from Devastating Onslaught.
Resolve the nontoken Biovisionary's trigger, causing you to win the game.

Win the game

Biovisionary

Cast Devastating Onslaught by paying {2}{R}, targeting a creature you control.
Holding priority, cast Naru Meha by paying {2}{U}{U}.
When Naru Meha enters the battlefield, it triggers, copying Devastating Onslaught, targeting Naru Meha.
Resolve the copy of Devastating Onslaught, creating a token copy of Naru Meha.
Put either Naru Meha into your graveyard due to the legend rule.
Repeat from step 3.

Combos with "Devastating Onslaught"