Someone recently mentioned to me that there is a "law of magic/karma" and keeps insisting that magic isn't bound to what is realistic, but instead to this "law" does anyone else know what this is?
They may be talking about the concept of harmful magic coming back to you in some way. I've even read about a version of that saying that even if the magic wasn't meant to be harmful, it'll come back to you somehow if harm is done as a result of it. Wiccans of course believe in the threefold law, which states that whatever you do will come back to you three times over, good or bad.
Maybe they're talking about the universal laws and more specifically the law of attraction?
At a basic form the law of attraction just says that you attract what you are being, for instance through your thoughts and beliefs you could attract something similar.
I hope this helps :)
I think they have a view similar to the rule of three. It's the belief whatever you do [good or bad] comes back three times [also see rule of seven, rule of thirteen and I think rule of twenty-one but don't quote me] Karma is a concept most in the west don't really understand. They think you cut someone off in traffic then get a speeding ticket that's karma, but karma determines your next life [and that's just a basic explanation] This being said, there are witches who believe the universe keeps score and rewards/punishes accordingly.
Personally, while I feel the universe has a way of balancing things out. The morality of human society isn't a universal law [just compare it to faerie morals, I've heard saying thank you is apparently offensive] So, who's to say casting a spell to kill a person who wronged you isn't viewed as a positive by the universe? Things like the Wiccan Rede, Threefold Law, Law of Attraction, Karma and so on are great ideas to base your morals/ethics on, but I don't think there is one universal rule when it comes to what governs magick.
The only rule I know as fact in witchcraft is that magick on the physical plane is ruled by nature and adheres to natural laws. If something isn't in human nature [flight, shapeshifting, teleportation] magick won't make it physically possible because it wound contradict nature. On other planes of existence, there's more wiggle room as magick acts differently in those realms. But here in our plane of existence, nature has the final say.