Agatha's Soul Cauldron + Grist, the Hunger Tide + Good-Fortune Unicorn
Infinite ETB, Infinite self-mill, Infinite creature tokens
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.
When the Insect enters, Good-Fortune Unicorn triggers, putting a +1/+1 counter on the Insect. This causes it to gain Grist's abilities due to Agatha's Soul Cauldron.
Repeat from step 1 using the Insect token instead.
Component Cards
How It Works
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.
When the Insect enters, Good-Fortune Unicorn triggers, putting a +1/+1 counter on the Insect
This causes it to gain Grist's abilities due to Agatha's Soul Cauldron.
Repeat from step 1 using the Insect token instead.