Wight of the Reliquary + Agatha's Soul Cauldron + Bloodghast + Insidious Roots + Concordant Crossroads

Wight of the Reliquary

Agatha's Soul Cauldron

Bloodghast

Insidious Roots

Concordant Crossroads

How it works

1. Activate a creature you control that has a +1/+1 counter on it by tapping it and sacrificing Bloodghast, searching your library for a land card and putting it onto the battlefield tapped.
2. When the land enters, Bloodghast triggers, returning itself from your graveyard to the battlefield tapped.
3. Insidious Roots triggers, creating a 0/1 Plant creature token and then putting a +1/+1 counter on each Plant you control.
4. Repeat using the Plant instead until no lands are in your library.

This engine relies on Agatha's Soul Cauldron to grant Wight of the Reliquary's powerful land-tutoring sacrifice ability to any creature bearing a +1/+1 counter. Concordant Crossroads ensures your newly created tokens can tap right away, while Bloodghast provides the initial recursive sacrifice fodder. Every time you sacrifice Bloodghast to find a land, its landfall ability returns it to the battlefield, causing Insidious Roots to spawn a Plant token and place a fresh +1/+1 counter to keep the cauldron-fueled loop going indefinitely.