Cast Oathsworn Vampire either from your hand or graveyard by paying 1.
Edgar triggers, creating a 1/1 Vampire creature token.
Activate Warren Soultrader by paying 1 life and sacrificing Oathsworn Vampire.
When Oathsworn Vampire dies, Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel triggers, causing target opponent to lose 1 life and you to gain 1 life.
Resolve the Warren Soultrader ability, creating a Treasure token.
Repeat steps 3 through 5 once, sacrificing the Vampire token instead.
Activate two Treasures by tapping and sacrificing them, adding 1.
Repeat.
This loop works by leveraging Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel's passive drain ability to continuously offset the life payments required to fuel Warren Soultrader's sacrifice outlet. Each time Oathsworn Vampire is sacrificed to generate a Treasure and a life drain, Edgar Markov's *Eminence* ability steps in to hand you a free Vampire token replacement. That newly gained life enables you to recast Oathsworn Vampire directly from your graveyard, while the generated Treasures provide the exact black mana needed to repeat the cycle infinitely.