Agatha's Soul Cauldron + Inquisitive Puppet + Sigil Captain

Agatha's Soul Cauldron

Inquisitive Puppet

Sigil Captain

How it works

1. Activate another creature you control that has a +1/+1 counter on it by exiling it, creating a 1/1 Human creature token.
2. When the Human enters the battlefield, Sigil Captain triggers, putting two +1/+1 counters on it.
3. Repeat using the Human token instead.

This clever loop transforms an ordinary token maker into an infinite engine by feeding on its own byproduct. With Agatha's Soul Cauldron granting the activated exile ability of Inquisitive Puppet to your creatures, you can sacrifice a creature to generate a 1/1 token and load up the Cauldron's graveyard-hate utility at the same time. Enter Sigil Captain, whose static anthem effect turns that newly minted 1/1 into a 3/3 powerhouse the moment it hits the battlefield. Because that token now carries the necessary +1/+1 counters to fuel the process, it can immediately tap to exile itself via Agatha's Soul Cauldron and repeat the cycle indefinitely.