You control a creature that has a +1/+1 counter on it.
Mana Needed
({1} magic symbol) ({R} magic symbol) available.
Steps
Cast
First Day of Class by paying ({1} magic symbol) ({R} magic symbol) .
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,
First Day of Class 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 2 using the Insect token instead.