There is an online spell book that is within your access of use. Please feel free to go through it and find a spell or to write your own.
Many different cultures have different practices outside of the regular use of "spells" that can also cause these effects. For example, in Hoodoo and Conjure workings, you can set nails or even pentagrams over a path that this person, whom you want to inflict pain on, walks on daily. There is even my personal favorite which is drawing up as much negative energy as possible about a particular person and sending it to them to help promote their suffering. The possibilities are endless.
Yes, there are even more traditional ways of causing harm but I am not suggesting that you get in trouble with the law for committing a violent act.
I think if you feel like you "need" to cause someone pain, then you legitimately need a mental health evaluation. That's not a jab or an insult. It's incredibly concerning when someone so lacks the basic human empathy and compassion to the point that they can conceive of torturing a person with no thoughts of the moral ramifications. Especially if they feel like they need to torture a person.
To be completely honest, it is not unusual for someone to want to cause someone pain or harm within reason nor is it much of a disability especially when you are seeking revenge. Typically, disabilities relating to harm would involve actually going out and doing it due to mental incapability; however, most disabilities do not relate to violence which is a general misconception among the public. In fact, a 2014 study enacted by the American Psychological Association showed that mental illnesses are not directly linked to any sort of crime. They did diagnosed those with serious mental disorders and only 7.5 percent of crimes were of related symptoms towards that disorder.
Human empathy and compassion is different from person to person & has its limits. For some people, it may only extend to an individual's own social group. I am taking a sociology class for four and half months which is generally helpful for learning about these different social behaviors and groups so I wouldn't say that they lack empathy. Needless to say, morals and mores are also dependent on a particular social group and society.
Peccator, although you might believe that your being helpful, your not. Another person posted a similar comment on a thread that I started, and was extremely rude. Wanting to inflict pain on someone IS NOT a mental instability in the vast majority of criminal actions. I would recommend you take time to understand someone's post before you reply. If you can't provide help, or what is asked on a thread do not post, it is as simple as that.
Enabling violence is just as bad as inflicting it. Coming to a magick site and asking for a curse to inflict pain is as wrong as going to a cutlery shop and asking which butcher knife is best for stabbing people with.
In the case of the guy stabbing someone, it maybe his opinion that it's okay to stab people. That doesn't make it okay. There's nowhere in the world that stabbing people is an acceptable thing. That makes it universal, not opinion. Violence is always wrong. Whether it's inflicted via physical means or magical is just details.
Each social group is different even if their morals only pertain to their particular group. This is just your opinion of right and wrong though but laws are there that the majority agrees on. Regardless, we are talking about the magic in this case and not actually stabbing someone.