Quilled Greatwurm + Crystalline Crawler + Aggravated Assault

Quilled Greatwurm

Crystalline Crawler

Aggravated Assault

How it works

1. Deal combat damage using Crystalline Crawler.
2. Quilled Greatwurm triggers, putting that many +1/+1 counters on Crystalline Crawler.
3. Move to your postcombat main phase.
4. Activate Crystalline Crawler's first ability five times by removing five +1/+1 counters from it, adding 3.
5. Activate Aggravated Assault by paying 3, untapping all creatures you control and causing you to get an additional combat and main phase after this one.
6. Repeat.

This clever loop lets Crystalline Crawler become a self-sustaining engine of infinite combat phases and mana. When the Crawler attacks and deals damage, Quilled Greatwurm triggers to reward that combat damage by heavily stacking +1/+1 counters back onto the creature, all while Aggravated Assault stands ready to grant endless extra attack steps and main phases in exchange for the mana those counters provide.