Agatha's Soul Cauldron + Grist, the Hunger Tide + Cathars' Crusade

Agatha's Soul Cauldron

Grist, the Hunger Tide

Cathars' Crusade

How it works

1. Activate a creature using Grist's first loyalty ability by putting a loyalty counter on it, causing you to create a 1/1 Insect creature token and mill a card, and then put a loyalty counter on the creature and repeat the process if the card was an Insect.
2. When the Insect enters, Cathars' Crusade triggers, putting a +1/+1 counter on each creature you control. This causes the Insect to gain Grist's abilities due to Agatha's Soul Cauldron.
3. Repeat from step 1 using the Insect token instead.

This clever loop turns Grist, the Hunger Tide into a powerhouse sitting in your graveyard, ready to be channeled through Agatha's Soul Cauldron. The Cauldron grants Grist's activated abilities to your creatures with +1/+1 counters, allowing a creature you control to tap and use Grist's first loyalty ability to create Insect tokens and mill cards. Every time a new token arrives, Cathars' Crusade triggers to pump your board with +1/+1 counters, which in turn feeds the Cauldron's ongoing stat requirements and keeps the chain of activations going infinitely.