NOTE: The concoction you decide to use will be PERMANENTLY unusable on this character.
I recommend the Tranquility Font
Start by buying 2 and only 2 of the concoction. Drink one, then quick slot the last.
Cast miasma and spam the quick slot button the concoction is in. (This can be made easier by having some Consumable Use Speed) but is not required as I'm on a brand new character in the video
If done correctly, miasma will still cast but not make the full sound at the end. Finish the drinking animation of the concoction and it will go to -1
You can now sell that concoction indefinitely for unlimited scrap!
Some extra notes; If miasma casts but still makes the full sound, you can Dodge out of the drinking animation to save it from being consumed (Mostly for anyone that might already be low on scrap and needs to save some in case they mess it up and drink it all the way)