Sek'Kuar, Deathkeeper | Warren Soultrader | Nether Traitor

(and one other card)

Activate
Warren Soultrader by sacrificing
Nether Traitor and paying 1 life.
When
Nether Traitor dies,
Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel and
Sek'Kuar trigger.
Resolve the
Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel trigger, causing you to gain 1 life and an opponent to lose 1 life.
Resolve the
Sek'Kuar trigger, creating a 3/1 Graveborn creature token.
Resolve the
Warren Soultrader ability, creating a Treasure token.
Activate the Treasure by tapping and sacrificing it, adding ({B} magic symbol) .
Activate
Warren Soultrader by paying 1 life and sacrificing the Graveborn.
When the Graveborn dies,
Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel and
Nether Traitor trigger.
Resolve the
Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel trigger, causing you to gain 1 life and an opponent to lose 1 life.
Resolve the
Nether Traitor trigger, causing you to pay ({B} magic symbol) to return
Nether Traitor from your graveyard to the battlefield.
Resolve the
Warren Soultrader ability, creating a Treasure token.
Repeat.

Whether
Sephiroth, Fabled SOLDIER or
Sephiroth, One-Winged Angel is on the battlefield, the combo will function, either by using
Sephiroth, Fabled SOLDIER's ability or the ability from
Sephiroth, One-Winged Angel's emblem.