Will a misguided prayer intending to harm someone end up with Lucifer instead of Creator, and if so, by what mechanism?

In a general sense, this is true. And by Lucifer as part of the answer, we mean the entire group of dark spirits, the spirit meddler cohort. This is because energy is universal and can be universally tuned into and recognized by a consciousness which is present in all of creation. In the fullest sense, all the universe hears your thoughts and words. This is literally true, although consciousness can be focused and de-focused. Therefore, this is why people vary in their intuitive sensing, ranging from those who are completely cut off from anything beyond the normal senses, to the extreme empath who is continually bombarded by energies they sense and take in, to their detriment in many cases. The mechanism is, once negativity is launched in terms of a dark intention for someone, this energy goes out into the universe and can be sensed and perceived and then followed to its target. This you have been told before, that many times spirits ride the energy of a dark thought, like a curse, and gain entry through the aura of the intended victim in this fashion, by piggybacking and using that curse energy as a carrier wave to enable the penetration to occur, as it is a form of attacking energy designed to impinge on the target to cause harm. This is simply resonance, like seeking like. Like being aware of like and acting accordingly. It is not actively referred on by Creator to the lower order beings, it is simply their ability to see these energies and utilize them in various ways for their benefit that you see taking place.