It depends on what you're asking for exactly. [I assume you mean a justice spell since karma is decided by the cosmos and not individuals]
Example: someone stole your partner, so you want them to feel bad. You can cast a justice spell, which should punish someone without going overboard. The issue lies in whether or not you would feel okay with the outcome. Normally, in a situation like someone backstabbing you, they would be caught lying or someone would betray them. However, sometimes it could result in something worse. Say you're going to court, the justice spell could bankrupt someone, send them to jail, and perhaps the death penalty if they murdered a loved one. Would you be okay with this? Would your conscious be fine knowing you ruined someone's life because they caused harm to you first? [again, justice spells usually balance the scales, so a stolen phone wouldn't result in them being hit by a bus, but you should ask yourself if you're fine seeing this person crying because something they loved was stolen] The only time's a justice spell would backfire and harm you is if you're the guilty party or the other person is a witch and reversed the casting.
If you're going darker, and want to hex them, this could cause ill effects to you. Not only you feeling guilty they're hurt once you've calmed down [hexes and curses are usually done in enraged states because you need negative energy] but you've built up negative energy which could linger and affect you in a variety of ways. The spell could also backfire [especially if this is a witch you're casting on, they could have protections or know how to counter a hex and send it back to you worse] Even if they're not a witch or magickal practitioner, there could be protections shielding them. If they're religious in any way, their deities could be watching them, they could have ancestors or guardian spirits watching them, even pets or plants, if treated right, could deflect spells sent their way [good or bad]
Overall, you should consider the situation and the specific spell over wondering if an entire category of spells are good or bad, safe or unsafe.
Thank you. I didn't ask for anything so grotesque, I just wanted the person to learn their lesson (in the right measure). My intention is not to kill anyone.
