Cast Ad Nauseam by paying {3}{B}{B}.
Resolve Ad Nauseam, revealing the top card of your library, putting that card into your hand and losing life equal to that card's mana value.
Repeat the process in step 2 as many times as desired.

Infinite card draw

Ad Nauseam

Soul Echo

At the beginning of your upkeep, Axis of Mortality triggers.
Activate Wall of Blood by paying 1 life, giving Wall of Blood +1/+1 until end of turn.
Repeat step 2 until you have zero life.
Resolve the Axis of Mortality trigger, swapping your life total with an opponent.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

Target player loses the game on each of your turns

Axis of Mortality

Wall of Blood

At the beginning of your upkeep, Axis of Mortality triggers.
Activate Necropotence by paying 1 life, exiling the top card of your library face down.
Repeat step 2 until you have zero life.
Resolve the Axis of Mortality trigger, swapping your life total with an opponent.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

Necropotence

Activate Wall of Blood by paying 1 life, giving Wall of Blood +1/+1 until end of turn.
Repeat step 1 until you have zero life.
Activate Soul Conduit by paying {6} and tapping it, exchanging your life total with an opponent's.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

Soul Conduit

Activate Wall of Blood by paying life.
Repeat step 1 until you have 0 life.
Cast Mister Negative by paying {5}{W}{B} plus commander tax if applicable.
When Mister Negative enters, it triggers, swapping your life total with an opponent's.
The opponent loses the game due to having 0 life.

Near-infinite lifeloss for target opponent

Target opponent loses the game

Mister Negative

At the beginning of your upkeep, Axis of Mortality triggers.
Activate Blood Celebrant by paying {B} and one life, adding {B}.
Repeat step 2 until you have zero life.
Resolve the Axis of Mortality trigger, swapping your life total with an opponent.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

Blood Celebrant

During your upkeep, activate Wall of Blood by paying 1 life, giving Wall of Blood +1/+1 until end of turn.
Repeat step 1 until you have zero life.
Activate Magus of the Mirror by tapping and sacrificing it, exchanging your life total with an opponent.
The opponent loses the game due to having zero life.

Target player loses the game

Magus of the Mirror

Activate Blood Celebrant by paying {B} and one life, adding {B}.
Repeat step 1 until you have zero life.
Activate Soul Conduit by paying {6} and tapping it, exchanging your life total with an opponent's.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

Activate Necropotence by paying 1 life, exiling the top card of your library face down.
Repeat step 1 until you have zero life.
Activate Soul Conduit by paying {6} and tapping it, exchanging your life total with an opponent's.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

During your upkeep, activate Blood Celebrant by paying {B} and one life, adding {B}.
Repeat step 1 until you have zero life.
Activate Magus of the Mirror by tapping and sacrificing it, exchanging your life total with an opponent.
The opponent loses the game due to having zero life.

During your upkeep, activate Necropotence by paying 1 life, exiling the top card of your library face down.
Repeat step 1 until you have zero life.
Activate Magus of the Mirror by tapping and sacrificing it, exchanging your life total with an opponent.
The opponent loses the game due to having zero life.

At the beginning of your upkeep, Axis of Mortality triggers.
Activate Ethereal Champion by paying 1 life, preventing the next one damage that will be dealt to Ethereal Champion this turn.
Repeat step 2 until you have zero life.
Resolve the Axis of Mortality trigger, swapping your life total with an opponent.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

Ethereal Champion

Activate Ethereal Champion by paying 1 life, preventing the next one damage that will be dealt to Ethereal Champion this turn.
Repeat step 1 until you have zero life.
Activate Soul Conduit by paying {6} and tapping it, exchanging your life total with an opponent's.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

During your upkeep, activate Ethereal Champion by paying 1 life, preventing the next one damage that will be dealt to Ethereal Champion this turn.
Repeat step 1 until you have zero life.
Activate Magus of the Mirror by tapping and sacrificing it, exchanging your life total with an opponent.
The opponent loses the game due to having zero life.

Activate Cavern Harpy by paying 1 life.
Repeat step 1 until you have zero life.
Resolve the last Cavern Harpy trigger, returning it to your hand.
The remaining Cavern Harpy triggers fizzle.
Activate Soul Conduit by paying {6} and tapping it, exchanging your life total with an opponent's.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

Cavern Harpy

At the beginning of your upkeep, Axis of Mortality triggers.
Activate Cavern Harpy by paying 1 life.
Repeat step 2 until you have zero life.
Resolve the last Cavern Harpy trigger, returning it to your hand.
The remaining Cavern Harpy triggers fizzle.
Resolve the Axis of Mortality trigger, swapping your life total with an opponent.
The opponent loses the game due to having zero life.
You may repeat this on each of your turns.

During your upkeep, activate Cavern Harpy by paying 1 life.
Repeat step 1 until you have zero life.
Resolve the last Cavern Harpy trigger, returning it to your hand.
The remaining Cavern Harpy triggers fizzle.
Activate Magus of the Mirror by tapping and sacrificing it, exchanging your life total with an opponent.
The opponent loses the game due to having zero life.

Combos with "Soul Echo"