Activate Selenia by paying 2 life.
Repeat step 2 until you have 0 life.
Resolve all Selenia abilities.
Cast Repay in Kind by paying {5}{B}{B}, causing each opponent's life total to become 0.
Each opponent loses the game as a state-based action due to having 0 life.

Each opponent loses the game

Near-infinite lifeloss for all players

Permanent with "You don't lose the game due to having 0 or less life"

Repay in Kind

Selenia, Dark Angel

On the end step prior to your turn, activate Selenia by paying 2 life.
Repeat step 1 until you have one life.
Resolve the first Selenia trigger, returning it from your graveyard to your hand.
All remaining Selenia triggers fail to resolve due to it no longer being on the battlefield.
At the beginning of your upkeep, Near-Death Experience triggers, causing you to win the game.

Win the game at the beginning of your next upkeep

Near-Death Experience

Activate Vizkopa Guildmage's second ability by paying {1}{W}{B}, causing each opponent to lose life whenever you gain life this turn.
Activate Selenia by paying 2 life.
Repeat step 2 until you have 2 or less life.
Activate Children of Korils by sacrificing it, causing you to gain life equal to the amount of life you've lost this turn.
Vizkopa Guildmage triggers, causing each opponent to lose life equal to the amount of life you gained.

Near-infinite lifeloss

Children of Korlis

Vizkopa Guildmage

Activate Selenia 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

Phyrexian Unlife

Activate Selenia by paying 2 life.
Vilis triggers, causing you to draw two cards.
Sheoldred's first ability triggers twice, causing you to gain 4 life.
Repeat as desired.
Resolve all Selenia abilities.

Infinite card draw

Near-infinite lifegain

Near-infinite lifegain triggers

Infinite draw triggers

Sheoldred, the Apocalypse

Vilis, Broker of Blood

Activate Selenia by paying life.
Repeat step 1 as desired.
Activate Rowan by tapping it, reducing the cost of all black and/or red spells you cast this turn.
Cast Exsanguinate, choosing for X to equal the amount of life you've lost this turn, but paying a total of {B}{B} due to Rowan.
Resolve Exsanguinate, causing each opponent to lose X life, and you to gain life equal to the life lost this way.

Rowan, Scion of War

Exsanguinate

Activate Selenia by paying 2 life.
Repeat step 1 until Greven has power 21 or greater due to its first ability.
Deal combat damage to an opponent using Greven. The opponent loses the game due to being dealt 21 or more combat damage from your commander.

Greven, Predator Captain

Activate Selenia by paying life.
Repeat step 1 as desired.
Activate Rowan by tapping it, reducing the cost of all black and/or red spells you cast this turn.
Cast a copy of Exsanguinate, choosing for X to equal the amount of life you've lost this turn, but paying a total of {B}{B} due to Rowan.
Resolve Exsanguinate, causing each opponent to lose X life, and you to gain life equal to the life lost this way.

Combos with "Selenia, Dark Angel"