Mortuary + Cauldron Familiar + Woe Strider + Bolas's Citadel

Mortuary

Cauldron Familiar

Woe Strider

Bolas's Citadel

How it works

1. Cast Cauldron Familiar either from your hand or from the top of your library by paying or 1 life respectively.
2. When Cauldron Familiar enters, it triggers, causing each opponent to lose 1 life and you to gain 1 life.
3. Activate Woe Strider by sacrificing Cauldron Familiar.
4. When Cauldron Familiar dies, Mortuary triggers, putting Cauldron Familiar from your graveyard onto the top of your library.
5. Resolve the Woe Strider ability.
6. Repeat.

This loop transforms your library into an endless cycle of life-drain and sacrifices, fueled entirely by the top-deck manipulation of Mortuary. With Bolas's Citadel allowing you to cast Cauldron Familiar straight from the top of your library for a mere 1 life rather than its usual mana cost, you can repeatedly deploy the cat and feed it to Woe Strider's sacrifice outlet. Every time Cauldron Familiar dies, Mortuary catches it and places it right back onto the top of your library, setting it up to be recast instantly by Bolas's Citadel's static ability.