Vigor + Hanabi Blast + Crystalline Crawler + Oskar, Rubbish Reclaimer + City on Fire

Vigor

Hanabi Blast

Crystalline Crawler

Oskar, Rubbish Reclaimer

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. Oskar triggers if the discarded card was a nonland card.
4. Holding priority, activate Crystalline Crawler;s first ability three times by removing three +1/+1 counters from it, adding 1.
5. Resolve the Oskar trigger, choosing to cast Hanabi Blast if it was the discarded card by paying 1 targeting Crystalline Crawler, or choosing not to cast the card otherwise.
6. If you did not cast Hanabi Blast using Oskar, cast it from your hand by paying 1, targeting Crystalline Crawler.
7. Repeat from step 2.
8. Once you have infinite colored mana, you may instead target any other creature and/or player with Hanabi Blast.

This clever loop turns damage into an endless font of mana by leveraging Vigor's replacement effect to turn Hanabi Blast's self-inflicted damage into a massive pile of +1/+1 counters on Crystalline Crawler. You then strip those counters away for colored mana, while City on Fire's damage-tripling static ability ensures that Vigor grows your creatures even faster if you direct the blast elsewhere once the engine is running. To keep the loop going, Oskar, Rubbish Reclaimer steps in as the enabler, allowing you to cast Hanabi Blast directly from the graveyard whenever the random discard requirement puts it there.