See my story How I lost my virginity in a threesome
It’s hardly the most impressive story I’ve got, but It’s the one I like to talk about most. 
I think the most impressive (and scariest) curse I have thrown was with the help of Hecate. A friend of mine had some false rape allegations made against him. He managed to come out of it without a conviction because the girl was caught in a lie. She had actually bragged to one of her cousins that she was able to ruin the guys life so easily… all because he called her fat. Her cousin didn’t think that was very cool and decided to testify in favor of my friend.
Proven innocent or not it didn’t help my friend. His life was still torn apart. He lost his job, his wife left him, and he lost custody of his kids because of the allegations. On top of all the other BS, this woman didn’t serve a day in jail because she lied under oath. He showed up on my doorstep in tears asking for some revenge. So I stepped in.
About a week after I did the curse this woman decided one day to take (according to her friends) a very uncharacteristic walk through the park. She was in a rather remote area of the park (it is quite large) when she was attacked by a homeless man, beaten, raped and left for dead. She laid in that part of the park for about two hours bleeding. When she was found by a woman going for a jog. She was rushed to the hospital and spent two weeks in there for recovery. About a week after she got out, She returned to work for the first time, that night she worked the closing shift and was walking to her car in the parking lot at night. When a pack of wild dogs attacked her and killed her. There has never been a pack of wild dogs reported in that area.
This IS the wildest experience I have had with a spirit. I’m relatively un-phasable when it comes to horrible things happening in response to my rituals. I usually get exactly what I intended. But this time I gave Hecate license to decide how the curse would manifest. This honestly dropped my jaw at its complete and utter brutality. I have seen and done a lot… but the way this curse manifested honestly terrified me. I guess Hecate didn’t like false witness either. DON"T UNDERESTIMATE HACATE!
@CharlieP7 Not sure if this is what you wanted, or if you had something less graphic in mind. But this was something huge, that I felt might be worth mentioning.