The Thirteenth Doctor + Squee, the Immortal + Crystalline Crawler + Phyrexian Altar + Pir, Imaginative Rascal

The Thirteenth Doctor

Squee, the Immortal

Crystalline Crawler

Phyrexian Altar

Pir, Imaginative Rascal

How it works

1. Activate Phyrexian Altar by sacrificing Squee, adding .
2. Cast Squee from your graveyard by paying 1.
3. The Thirteenth Doctor's first ability triggers, putting two +1/+1 counters on Crystalline Crawler.
4. Activate Crystalline Crawler's first ability twice by removing two +1/+1 counters from it, adding 1.
5. Repeat.

This recursive loop turns Squee, the Immortal into an endlessly recurring sacrifice engine by letting you repeatedly cast him from the graveyard after feeding him to Phyrexian Altar. Every time Squee hits the stack from exile, The Thirteenth Doctor triggers, allowing you to seed Crystalline Crawler with fresh counters—a process supercharged by Pir, Imaginative Rascal's replacement effect to ensure you always get extra counters for your trouble. You then strip those counters off Crystalline Crawler for mana to help fund Squee's recurring cost, yielding an endless engine of sacrifices, storm count, and creature triggers.