i tried to take revenge against my enemies with demons without much success. I am looking to learn about fast.and lethal curses
Fast and lethal might be a problem. Magic can take time to work, especially baneful. That being said, I would look into the Necronomicon. While there are hangs up with the book, the beings are not demonic but I did have some pretty clear signs of success fairly quickly with Zahgurim.
And of course Baneful Magick by EA is a good book on the subject. So is Magical Attack by Gordon Winterfield
Did you use the method described in Baneful magick? It feels weird not to actually call Zahgurim by name during the consecration.
I make a puppet of the subject and then call on Belial and bind the target so they may not save themselves and then I summon their soul into the poppet and stab it. Instead of the poppet you can also use a chicken head as a fetish link.
How did you summon their soul into the poppet???
The act of summoning the soul of the living victim is rather common in occult. I personally get possessed by Demons who correspond To my desire.