Agatha's Soul Cauldron + Deeproot Pilgrimage + North Pole Patrol

Agatha's Soul Cauldron

Deeproot Pilgrimage

North Pole Patrol

How it works

1. Activate the nontoken Merfolk using North Pole Patrol's ability by tapping it.
2. Deeproot Pilgrimage triggers, creating a 1/1 Merfolk creature token.
3. Resolve the Merfolk's ability, untapping the other creature.
4. Activate the other creature using North Pole Patrol's ability by tapping it, untapping the nontoken Merfolk.
5. Repeat.

This clever loop turns North Pole Patrol into a self-sustaining engine by granting its tap ability to other creatures via Agatha's Soul Cauldron, allowing you to repeatedly tap and untap your board. As the nontoken Merfolk taps to activate this ability, Deeproot Pilgrimage notices the tap and immediately triggers to reward you with a brand-new Merfolk token. Because Agatha's Soul Cauldron also conveniently lets you spend your mana as though it were any color, you have all the flexibility you need to set up this recursive dance and flood the battlefield with an endless tide of creatures.