Cast Peer into the Abyss by paying {4}{B}{B}{B}, causing you to draw half your library and lose half your life total, rounding up each time.
Psychosis Crawler triggers for each card you drew, causing each opponent to lose life equal to the number of cards you drew.

Near-infinite lifeloss

Near-infinite card draw

Near-infinite draw triggers

Psychosis Crawler

Peer into the Abyss

Draw a card.
Psychosis Crawler triggers, causing each opponent to lose 1 life.
Kefka triggers, causing you to draw a card.
Repeat from step 2.

Infinite card draw

Infinite draw triggers

Kefka, Court Mage // Kefka, Ruler of Ruin

Cast Enter the Infinite by paying {8}{U}{U}{U}{U}, causing you to draw your library and then put a card on top of your library.
Psychosis Crawler triggers for each card drawn, causing each opponent to lose that much life.

Enter the Infinite

Cast Windfall by paying {2}{U}, causing each player to discard their hand and each opponent to draw cards equal to the greatest number of cards discarded this way, and you to draw twice that number due to Teferi's Ageless Insight.
Psychosis Crawler triggers for each card you draw, and Scrawling Crawler triggers for each card opponents draw.
Resolve the Psychosis Crawler triggers, causing each opponent to lose 1 life for each card you drew.
Resolve the Scrawling Crawler triggers, causing each opponent to lose 1 life for each card they drew.

Scrawling Crawler

Windfall

Teferi's Ageless Insight

Draw a card.
Psychosis Crawler triggers, causing each opponent to lose 1 life.
Exquisite Blood triggers for each opponent.
Resolve the first Exquisite Blood trigger, causing you to gain 1 life.
Drogskol Reaver triggers, causing you to draw a card.
Repeat from step 2.

Combos with "Psychosis Crawler"