Anthony and all---
Have you created or adapted any rules for magical backlash from scrying in AD&D?
Trent Foster asked about this over on the Knights & Knaves Alehouse, and it's an interesting topic: https://knights-n-knaves.com/phpbb3/viewtopic.php?f=8&t=16227
I'm so lucky with my player group. Game designers tend to think in similar ways. And they treat the world and its inhabitants as real threats with real motives. Of course, if you play those kinds of games AGAINST the players, they will learn quickly! I rolled up some urban hazards for my group and the results showed that Albin, the fighter had been robbed during the month. Turning dice rolls into narrative, I explained that he'd been drinking and unwisely staggered home. That was when he'd been jumped. His magic shield was taken from him.
Now, before you say how harsh I am and ask how I manage it when players claim that their characters would never do any such thing, I'll just say that I've worked these sorts of procedural roles into character lives from the beginning and I've always prefaced it with, "your character is not a robot. your character is a real person with real proclivities, desires, and so on. Dice have generated crushes, marriages, assassination attempts, robberies, drug binges and more. They've also generated tips, fame, extra cash and other lucky events. As a result, the characters have much richer lives than what I think you'd normally get from sitting around a table.
That's all a long-winded way of saying that the magic shield WAS used to scry on the party by very bad guys and the party found out about it. This realization deepened their reliance on similarly devious tactics, much to my enjoyment.
Right. I think there's a fine line between discouraging an action and making the player think twice about abuse. The player who's been apprised of such threats starts to assess whether they should even attempt a scry on Orcus, for example, since it might meet with disaster. And If the target is a high level mage, perhaps it might be safer to try scrying on one of mage's servants for example. This could lead to more circuitous cloak and dagger, clues and so forth.
As a player I leverage divination magics as fully as possible, and as a DM I certainly encourage and reward their usage in my games. I don't want to discourage such behavior at all, since anything memorized that's not magic missile, fireball, or slow is often viewed as a wasted slot by many players (which is something I actively try to discourage!).
All that said, I do like these fun little sub-systems, and for magic to have certain resonating fingerprints that tag the caster for those in the know....
I know this is a late reply, but I don't think I actually need something like this. Powerful creatures and people are likely to to ward their lairs with things such as Symbols of Death specifically designed to trigger in event of scrying. Lower-brow, but medusa heads on pikes might serve a similar purpose.
The 12th level magic-user in my current campaign has a crystal ball and he uses it fairly often. But it was just last time (something like two sessions ago) when he used it and I told him to make a saving throw vs Petrification. He succeeded and was thoroughly rattled, immediately ending the scry.
Sometimes, you just have to remind players that everything has a risk, let their imaginations run wild, and balance is restored.