I’m a Shepard of Souls. I used to be able to get my thousands of souls from Unfinished Business in Spite, but now it requires Hell: Renown 10 instead of Connected: Hell 10 so I have a feeling I’m going to be locked out of that one for a while. Anyone have some tips as to where else to free souls other than straight up robbing the Brass Embassy?
Going from 5 renown to 10 is 40 cp, which is 6 favor turnins (using 7 favors) with the Brass Skull. I don’t know how often you flip cards but this shouldn’t take more than a month or so with playing once a day (remember you can get a ton of hell favors from Polite Invitations and the Afternoon of Good Deeds card).
Anywho, to actually answer your question… robbing the brass embassy is kinda bad and I wouldn’t recommend it. There’s thief’s cache expeditions which pay out 500 souls 40% of the time, but that’s not economical to grind with pure storylets (better to spend docks favors to get the supplies). I still personally have over 25000 souls from my hundreds of expeditions over the last year or so, though.
You might be best served grinding money your regular way and buying them. There’s paltry few sources of Souls in the game, all things considered, so you can also look over the wiki to see if any of them suit you: http://fallenlondon.wikia.com/wiki/Soul
Not a grind, but you can trade in criminal favours for souls using the “An Implausible Penance” card while you’re waiting to get your renown up.