The Thirteenth Doctor + Squee, the Immortal + Crystalline Crawler + Phyrexian Altar + Primal Vigor

The Thirteenth Doctor

Squee, the Immortal

Crystalline Crawler

Phyrexian Altar

Primal Vigor

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 ingenious loop turns Squee, the Immortal into an endlessly recurring engine, utilizing his unique ability to be cast directly from the graveyard. Whenever Squee is recast from that zone, The Thirteenth Doctor’s Paradox ability triggers, dropping counters onto Crystalline Crawler. Meanwhile, Primal Vigor doubles these incoming counters, leaving Crystalline Crawler flush with the resources needed to feed its mana-producing ability. By sacrificing Squee to Phyrexian Altar to generate the red mana needed to keep casting him, the engine generates an unstoppable loop of sacrifices and enters-the-battlefield triggers.