Mortuary + Bolas's Citadel + Phyrexian Dreadnought + Panicked Bystander // Cackling Culprit

Mortuary

Bolas's Citadel

Phyrexian Dreadnought

Panicked Bystander // Cackling Culprit

How it works

1. Cast Phyrexian Dreadnought from the top of your library by paying 1 life.
2. When Phyrexian Dreadnought enters, it triggers, causing you to sacrifice it.
3. When Phyrexian Dreadnought dies, Mortuary and Panicked Bystander // Cackling Culprit trigger.
4. Resolve the Mortuary trigger, putting Phyrexian Dreadnought from your graveyard onto the top of your library.
5. Resolve the Panicked Bystander // Cackling Culprit trigger, causing you to gain 1 life and each opponent to lose 1 life.
6. Repeat.