Pir, Imaginative Rascal + Tainted Observer + Animation Module + Crystalline Crawler + Tekuthal, Inquiry Dominus

Pir, Imaginative Rascal

Tainted Observer

Animation Module

Crystalline Crawler

Tekuthal, Inquiry Dominus

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. The Servo enters the battlefield, triggering Tainted Observer, causing you to pay 2 to put four +1/+1 counters on Crystalline Crawler.
4. Animation Module triggers four times.
5. Resolve the first three Animation Module triggers, choosing not to pay.
6. Activate Crystalline Crawler's first ability three times by removing three +1/+1 counters from it, adding 3.
7. Resolve the final Animation Module trigger, causing you to pay 1 to create a 1/1 Servo artifact creature token.
8. Repeat from step 3.

This intricate loop begins when you drop a +1/+1 counter on Crystalline Crawler, turning Animation Module into an engine that pumps out a 1/1 Servo artifact creature token. That new token entering the battlefield triggers Tainted Observer, which lets you pay {2} to proliferate; thanks to Pir, Imaginative Rascal, every instance of counter placement gets supercharged, rapidly stacking a wealth of +1/+1 counters back onto Crystalline Crawler. You can then feed those counters into Crystalline Crawler's mana ability to fund the Animation Module taxes, while Tekuthal, Inquiry Dominus stands ready to double your proliferation triggers if you choose to push the counter math even further.