I need to quickly raise my heartless to 4, what’s the easiest way to do this?
If you are a spirifer in the (fate-locked) Soul Trade, trading lots of souls for brass will get you there and far beyond in no time.
Otherwise you’ll probably have to rely on cards: Murdering Rubbery Men on the “Slime and Amber” card, siding with Hell on the Church/Hell conflict card, charging money on the “Rats next door”-card. Things like that. Just be a really bad person.
If you are already a PoSI, robbing crashed zailors on Mutton Island is a fast way to raise it. Not helping the lady on the Respectable Landau card or the Soft-Hearted Widow also works.