You could run pacts just to get free nivmagus triggers.

Gut Shot could be another way you could get "free" triggers. The life loss/damage output is at worst on parity, but with something like a Kiln Fiend, it ends up being 2 life lost for 4 bonus damage dealt.

Funkydiscogod I think Crash Through's cantrip effect is really important cuz else we run out of fuel rather quickly

I don't think Wandering Fumarole or Sulfur Falls are good here. Your deck is designed to win quickly, so tapped lands seem to hinder you. If you were playing control, or if you were running the Ceaseless Searblades + Wandering Fumarole combo then maybe. But not for this list. I would think you'd want to run Spirebluff Canal and a full playset of Steam Vents/Flooded Strand instead.

How has Stubborn Denial been btw? It kind of feels like a sideboard card (or at least not a four off mainboard) that you would swap in. I would have thought more burn/cantrips would have been the go for game one.