Vigor + Hanabi Blast + Crystalline Crawler + Conspiracy Theorist + City on Fire

Vigor

Hanabi Blast

Crystalline Crawler

Conspiracy Theorist

City on Fire

How it works

1. Cast Hanabi Blast by paying 1, targeting Crystalline Crawler.
2. Resolve Hanabi Blast, putting six +1/+1 counters on Crystalline Crawler due to Vigor's first ability, and then returning Hanabi Blast to your hand and discarding a card at random.
3. Conspiracy Theorist's second ability triggers, allowing you to exile the discarded card from your graveyard if it was a nonland card and cast it from exile this turn.
4. Activate Crystalline Crawler's first ability three times by removing three +1/+1 counters from it, adding 1.
5. Cast Hanabi Blast either from your hand or from exile by paying 1.
6. Repeat from step 2.
7. Once you have infinite colored mana, you may instead target any other creature and/or player with Hanabi Blast.

This loop turns self-inflicted damage into an engine for infinite mana, damage, and counters by leveraging Vigor to redirect Hanabi Blast's damage into Crystalline Crawler. Instead of destroying the Crawler, the damage is prevented entirely and converted into a massive pile of +1/+1 counters, which you can then strip away for colored mana. Meanwhile, Conspiracy Theorist catches whatever card you are forced to discard when casting Hanabi Blast, allowing you to recycle it right back out of exile. Finally, City on Fire sits on the board silently supercharging the loop, tripling the damage dealt to the Crawler to feed Vigor even more counters than you started with.