Hi Anna,
I asked my lecturer about when he had used it. He told me about a case where a woman had a really unusual autoimmune condition, and the remedy she had been doing well on had stoped working. He retook the case, and found the picture had not changed enough to warrent a new remedy, so asked for her permission to try potentised blood (he chose blood in her case because that was where the energetic disturbance was resonating). He made a 12c and a 10m. The 12c did nothing, the 10m apparently turned her whole case around, and she really started to do well after that. He said that other patients had not responded, so it is not something he uses often. If you like, I could send you his contact details, I'd just have to ask him first.