I've been trying to remember if we made it up, but I doubt it as I think that we all would have put up a fight and I seem to recall reading it. I'm going to look for it now. Think it was 2e. If I can find it I'll post it.It's certainly an interesting rule. And kind of preferable to the "Lies of Locke Lamora" style solutions. I feel like any idiot in a fantasy world who captured a mage would know to go for the full Lavinia, but your maimed PC's player would be (rightly) upset about that. That in turn means you've got to build special "mage shackles" or "anti-magic prison cells" instead, and that can feel heavy-handed. This unconscious bit is crazy-punishing if you get hit with the wrong end of a sleep spell, but I do like that it solves the other problem.