Xavier Sal, Infested Captain + Agatha's Soul Cauldron + Saproling Burst + Devoted Druid

Xavier Sal, Infested Captain

Agatha's Soul Cauldron

Saproling Burst

Devoted Druid

How it works

1. Activate Xavier Sal's second ability by tapping it and sacrificing another creature, putting a +1/+1 counter on it and a fade counter on Saproling Burst.
2. Activate Saproling Burst by removing a fade counter from it, creating a Saproling creature token.
3. Activate Xavier Sal using Devoted Druid's second ability by putting a -1/-1 counter on it, untapping Xavier Sal.
4. Repeat.

This intricate loop turns Saproling Burst into an inexhaustible engine by feeding its own fade counters back into play through Xavier Sal, Infested Captain. While Xavier Sal normally requires a sacrifice to proliferate and populate, Agatha's Soul Cauldron bridges the gap by granting creatures with +1/+1 counters the activated abilities of any creature cards exiled within it. By using the Cauldron to exile Devoted Druid and placing a counter on Xavier Sal, you gain the Druid's untap ability—allowing you to continually tap Xavier Sal to sacrifice tokens, proliferate your counters, and generate infinite death triggers, enter-the-battlefield triggers, and Saproling tokens.