At the beginning of your combat phase, Xenagos triggers, giving Malignus +X/+X until end of turn, where X is Malignus's power.
Cast Chandra's Ignition by paying {3}{R}{R}, causing Malignus to deal damage equal to its power to each other creature and each opponent.
Each opponent loses the game due to having zero or less life.

Near-infinite damage

Each opponent loses the game

Xenagos, God of Revels

Malignus

Chandra's Ignition

Cast Prossh by paying {3}{B}{R}{G} and commander tax, if applicable.
Prossh triggers, creating at least six 0/1 Kobold of Kher Keep creature tokens.
Activate Prossh six times by sacrificing six Kobold of Kher Keep tokens, giving Prossh +6/+0 until end of turn.
At the beginning of your combat phase, Xenagos triggers, giving Prossh +X/+X and haste until end of turn, where X is Prossh's power.
Deal combat damage to an opponent using Prossh, causing an opponent to be dealt at least twenty-two commander damage.
The opponent loses the game due to being dealt twenty-one or more combat damage by your commander.
Move to your postcombat main phase.
If Seize the Day is in your hand, cast it by paying {3}{R}.
Otherwise, cast it from your graveyard for its flashback cost by paying {2}{R}.
Resolve Sieze the Day, untapping Prossh and causing you to get an additional combat phase and main phase after this one.
Repeat from step 4 until each opponent has lost the game.

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