Mortuary + Narcomoeba + Undercity Informer + Pitiless Plunderer

Mortuary

Narcomoeba

Undercity Informer

Pitiless Plunderer

How it works

1. Activate Undercity Informer by paying 1 and sacrificing Narcomoeba.
2. When Narcomoeba dies, Mortuary and Pitiless Plunderer trigger.
3. Resolve the Mortuary trigger, putting Narcomoeba on top of your library from your graveyard.
4. Resolve the Pitiless Plunderer trigger, creating a Treasure token.
5. Resolve the Undercity Informer ability, causing you to put Narcomoeba into your graveyard from the top of your library.
6. Narcomoeba triggers, returning itself to the battlefield from your graveyard.
7. Activate the Treasure by tapping and sacrificing it, adding 1.
8. Repeat.

This elegant loop relies on Undercity Informer to mill through your deck, sacrificing Narcomoeba to fund the process while simultaneously fueling Pitiless Plunderer to generate the mana you need to keep going. Every time Narcomoeba hits the graveyard, Mortuary quietly intercepts it, placing the creature right back on top of your library so Undercity Informer can mill it straight back out again. Because Narcomoeba happily triggers its own return whenever it goes from your library to the graveyard, the cycle feeds itself endlessly with the help of Pitiless Plunderer's Treasure tokens.