Remembrance + Mortuary + Umbral Collar Zealot + Phyrexian Walker

Remembrance

Mortuary

Umbral Collar Zealot

Phyrexian Walker

How it works

1. Activate Umbral Collar Zealot by sacrificing Phyrexian Walker.
2. When Phyrexian Walker dies, Mortuary and Remembrance trigger.
3. Resolve the Mortuary trigger, putting Phyrexian Walker from your graveyard on top of your library.
4. Resolve the Remembrance trigger, searching your library for Phyrexian Walker and putting it into your hand.
5. Resolve the Umbral Collar Zealot ability.
6. Cast Phyrexian Walker by paying 0.
7. Repeat.