First there was an idea of using grenadins to power out Witching Hour.
Then came Combustion Cell.
And the deck started having so much mana and flow that the card quickly jumped from 2-off to a full playset. Stonescar Scrappers were turned into Direwood Prowlers, that you curve into on turn 4, after playing your Scraptank on turn 3. Combustion Cell allows the deck to play 4 Madness as removal. For the top-end you can play any combination of Red/Black big things you want. Gearcruncher is a must however. Witching Hour probably at this point of the deck is more a liability and less powerful than Gearcruncher or other nonsense legendaries like Venomspine, Valkyrie Harvester, or even Voprex. In the end, the deck went from a meme into a real deck so Witching Hours had to go, which gave us a better manabase as casting Kaleb on 6 is sometimes hard.
And the deck wins, surprisingly. Climbed from Diamond 3 to Masters quite easily. (especially after cutting Witching Hours and crafting 4 Gearcrunchers). Masters 6 is the best rank the deck has reached so far and hovers strongly in the top 10.
Cards tested and found bad: Sleepless Night (I never wanted to cast it as I didn't run out of cards), Stonescar Scrapper (It's a 6 mana play in the first place and being able to repeat it isn't worth having to sacrifice one additional creature compared to Direwood Prowler. Your grenadins are your ammo, love them), Witching Hour (6 influence is what kills this), Dark Wisp (You draw enough and rarely lack sac targets for your spells. It's a waste of time to play), Great-Kiln (Too many situational cards in the deck to get any real value from him)
Card to test: Valkyrie Harvester, Oblivion Spike, Toppletower (probably redundant), Miner's Musket, Venomspine Hydra
So much to test, so little shiftstone and time.
Edit: Deck is perfect now. Unless the meta changes dramatically, this version is what I'm going to run for the foreseeable future.
Edit2: Unitless decks are a pain with 8 board clears. Put in a few Sabos and Scrap Heap. Spark Hatcher > Shadowlands Guide, hands down. Sorry for doubting the little bugger. Miser Suffocate against Instigator, Kothon and Harbinger. Made a rudimentary sideboard.