Cause one or more opponents to lose life.
The Master of Lake-town triggers once for each life loss event, causing that player to mill cards equal to the amount of life lost.
Bloodchief Ascension triggers once for each card milled, causing that player to lose 2 life and you to gain 2 life for each trigger.
Repeat from step 2.

Infinite mill

Near-infinite lifegain

Near-infinite lifegain triggers

Near-infinite lifeloss

Bloodchief Ascension

The Master of Lake-town

Activate Duskmantle Guildmage's first ability by paying {1}{U}{B}, causing your opponent to lose life whenever a card is put into their graveyard this turn.
Activate Duskmantle Guildmage's second ability by paying {2}{U}{B}, causing an opponent to mill two cards.
Duskmantle Guildmage triggers twice.
Resolve the first trigger, causing the opponent to lose 1 life.
The Master of Lake-town triggers, causing the opponent to mill a card.
Duskmantle Guildmage triggers, causing the opponent to lose 1 life.
Repeat from step 5 until the opponent has a life total of zero, causing them to lose the game.
Repeat from step 2 for each other opponent.

Each opponent loses the game

Duskmantle Guildmage

Activate Ashnod's Altar by sacrificing The Master of Lake-town.
When The Master of Lake-town dies, it and Nim Deathmantle trigger.
Resolve the Master of Lake-town trigger, drawing a card for each graveyard that has seven or more cards in it.
Holding priority, activate Skirge Familiar by discarding a card, adding {B}.
Repeat step one additional time.
Resolve the Nim Deathmantle trigger, causing you to pay {4} to return The Master of Lake-town from your graveyard to the battlefield and attaching Nim Deathmantle to it.
Repeat.

Infinite draw triggers

Infinite looting

Infinite self-discard triggers

Near-infinite creature ETB

Near-infinite creature LTB

Near-infinite black mana

Near-infinite card draw

Near-infinite death triggers

Near-infinite creature sacrifice triggers

Nim Deathmantle

Skirge Familiar

Ashnod's Altar

Draw a card.
Human Torch triggers, dealing 1 damage to target opponent.
The Master of Lake-town triggers, causing that player to mill a card.
Since the card is black due to Painter's Servant, Compost triggers, allowing you to draw a card.
Repeat from step 2 until your library is empty or you decline to draw a card.

Combos with "The Master of Lake-town"