Mortuary + Bolas's Citadel + Accursed Centaur + Sifa Grent

Mortuary

Bolas's Citadel

Accursed Centaur

Sifa Grent

How it works

1. Cast Accursed Centaur from the top of your library by paying 1 life.
2. When Accursed Centaur enters, it triggers, causing you to sacrifice it.
3. When Accursed Centaur dies, Mortuary and Sifa Grent trigger.
4. Resolve the Mortuary trigger, putting Accursed Centaur from your graveyard onto the top of your library.
5. Resolve the Sifa Grent trigger, causing you to gain 1 life and target opponent to lose 1 life.
6. Repeat.

This ingenious loop uses Bolas's Citadel to cast Accursed Centaur straight from the top of your library for a mere 1 life instead of its mana cost. Once it enters the battlefield, Accursed Centaur immediately forces you to sacrifice a creature to its own triggered ability, sending it straight to the graveyard where Mortuary steps in to neatly place it right back on top of your library. Meanwhile, Sifa Grent watches the carnage unfold, turning every single death into a draining life swing that cancels out the life you paid into Bolas's Citadel and draining your opponents dry.