Concept Seed: Neomenancy.

Neomenancy

The great secret of the various types of divination is that, at first, they were all pretty absurd ways of going about the business.  After all, really: predicting the future from star patterns?  Entrails of random animals? Throwing sticks in the air? The absolute first time somebody tried any of those techniques, or any of the others, they must have felt like complete and total idiots.  And the divination method almost certainly didn’t work — at least until somebody sat down and made the blessed thing work from sheer force of will.

This is perfectly normal, as any professional thaumaturge might patiently explain: divination simply doesn’t function independently from sapient minds.  There are plenty of ‘natural’ magical phenomena, to be sure; but to predict the future there has to be something there observing the present.  It doesn’t have to be a mage, sure, but it does have to be at least self-aware.  

Which effectively means that every method of divination has to be carefully constructed, more or less from scratch.  Unfortunately, they’re also all highly idiosyncratic. They have to be; the more generic the divination method, the more useless it is.  Modern mages don’t even bother learning astrology or the I Ching anymore; popular usage has stripped them of any real esoteric juice. Tarot cards are virtually drained, at this point.  Dowsing still retains a little bit of oomph, but it’s fading fast. Generally, if the method can be found on the Internet, it’s mostly only worth learning for social engineering purposes.

But predicting the future would still be valuable!  That hasn’t changed; and that’s where Neomenancy comes in.  Basically, people adept in this combination of skillset and mindset will sit down and design self-contained, internally consistent divination methods.  The more specific, the better; this is cybernetic divination, where esoteric scripts are written to navigate through possibility matrices and communicate specific, germane data back to the diviner.  Preferably in as efficient (albeit extremely specialized) fashion as possible.

Naturally, new neomenantic divination methods are prime targets for industrial espionage.  As more people learn and use a particular neomenantic divination, it becomes less powerful; but usually up to a hundred mages can regularly perform any specific divination before it starts significantly degrading in usefulness. So there’s value in stealing the method — and also value in stealing the method, then wrecking a rival’s day by disseminating the method widely.  And where there is value, there is money.

And where there is money, there are people willing to do various jobs in order to collect that money.  Interesting tidbit of information: that bromide started out as part of a neomenantic method. Which didn’t last long, because it was just a little too good at being logical and internally self-consistent; so it lost its esoteric juice quickly, and they turned the mundane bits into ‘market capitalism.’  Waste not, want not.