When Wild Cantor dies, Mortuary and Funeral Room trigger.
Resolve the Mortuary trigger, putting Wild Cantor from your graveyard onto the top of your library.
Resolve the Funeral Room 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 Gwenom, Remorseless to turn the top of your library into an alternative casting hand where you pay life instead of mana. By sacrificing Wild Cantor for colored mana, you trigger its death sequence while Mortuary neatly recycles it right back onto the top of your library. Meanwhile, the unlocked Awakening Hall (the right half of Funeral Room // Awakening Hall) capitalizes on every single sacrifice by draining your opponents and padding your life total, which continuously fuels Gwenom's life-payment cost to replay Wild Cantor endlessly.