Animation Module + Sigil Captain + Krark-Clan Ironworks

Animation Module

Sigil Captain

Krark-Clan Ironworks

How it works

1. Put a +1/+1 counter on a creature you control.
2. Animation Module triggers, causing you to pay 1 to create a 1/1 Servo artifact creature token.
3. When the Servo enters the battlefield, Sigil Captain triggers, putting two +1/+1 counters on the Servo.
4. Animation Module triggers, holding priority, activate Krark-Clan Ironworks by sacrificing the Servo, adding CC.
5. Resolve the Animation Module trigger, causing you to pay 1 to create a 1/1 Servo artifact creature token.
6. Repeat from step 3.

This loop turns a single +1/+1 counter into a self-sustaining engine of creation and sacrifice, fueled by Animation Module's ability to breed Servos whenever counters are placed. As each 1/1 Servo artifact creature token enters the battlefield, Sigil Captain steps in to automatically upgrade it with two +1/+1 counters, which in turn triggers Animation Module all over again to keep the cycle rolling. To fuel the mana cost of Animation Module's triggered ability, Krark-Clan Ironworks happily accepts the newly minted Servo as a sacrifice, converting it into a surplus of colorless mana.