When Wild Cantor dies, Mortuary and Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel trigger.
Resolve the Mortuary trigger, putting Wild Cantor from your graveyard onto the top of your library.
Resolve the Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel trigger, causing you to gain 1 life and each opponent to lose 1 life.
Cast Wild Cantor from the top of your library by paying 1 life.
Repeat.
This loop relies on Mortuary to intercept Wild Cantor every time it heads to the graveyard, effortlessly recycling the little sacrifice outlet right back to the top of your library. From there, Gwenom, Remorseless steps in with its continuous permission to play cards from the top of your library, replacing the mana cost with a simple life payment that is easily offset by the steady lifegain generated along the way. Meanwhile, Sephiroth, Fabled SOLDIER // Sephiroth, One-Winged Angel watches the endless procession of dying creatures to drain your opponent's life total down to zero.