Tale of Katara and Toph + Animation Module + Nahiri's Resolve + Insidious Roots

Tale of Katara and Toph

Animation Module

Nahiri's Resolve

Insidious Roots

How it works

1. Activate a creature token by tapping it, adding 1.
2. The creature's ability granted to it by Tale of Katara and Toph triggers, putting a +1/+1 counter on the creature.
3. Animation Module triggers, causing you to pay 1 to create a 1/1 Servo artifact creature token.
4. Repeat.