Vigor + Hanabi Blast + Crystalline Crawler + Oskar, Rubbish Reclaimer + Angrath's Marauders

Vigor

Hanabi Blast

Crystalline Crawler

Oskar, Rubbish Reclaimer

Angrath's Marauders

How it works

1. Cast Hanabi Blast by paying 1, targeting Crystalline Crawler.
2. Resolve Hanabi Blast, putting four +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 loop turns the self-contained loop of Hanabi Blast into a self-sustaining engine by relying on Vigor to redirect the damage dealt to Crystalline Crawler into a massive windfall of +1/+1 counters. Those counters are then immediately cashed in for mana using Crystalline Crawler's ability to pay for the spell's repeated casting. Meanwhile, Oskar, Rubbish Reclaimer ensures that when Hanabi Blast is inevitably discarded to its own random discard clause, you can simply recast it right back out of the graveyard. To push the damage to lethal levels, Angrath's Marauders steps in to double every point of damage dealt, letting you easily pivot the entire setup from a mana engine into infinite damage.