Each spell that is cast on another, from my experience, has a link to the caster. For in order to cast a spell onto someone you must link it to them. So therefore it is possible to send the energy right back to the caster, if one can find the link that was established. It is the same concept as one who absorbs Energy. They establish a link to a person, or multiple people and drain their energy. You can reverse the tides by either reversing the effect back onto the one who established the link, or severing the link. To do this requires merely meditation, visualization, knowing what you are looking for which is a link that has an energy signature, or aura, that is not of your own, concentration, Will Power, and last, but not least Intent. Your Will needs to be stronger than the other persons in order to over power them. Other wise you will find yourself in a hole. Also, I advise caution, due to the factor it is not always easy to reflect Spells back at the caster. This is why Shielding is highly important. Yes, there are those who have worked for a long time learning to go right through others mental shields. Though, a strong shield can be built by grounding and centering yourself. Grounding is pushing the excess energy and distractions to the ground. It is also an exchange of energy, like breathing is, in with the oxygen(positive) out with the carbon dioxide(negative). Centering, you are the center, focus only on you and your energy. Visualization then comes into effect, to create a shield you need to be in a meditative stance. You need to have it designed to your specifications and reinforced by your will as well as intent. Constant grounding and centering is required for this. Eventually, you'll be able to ground and center to the point it becomes a mindset. Your mentality in this is vital. Once you have constructed a shield, you will be able to check it with mere visualization. You will know if your shield is weakening for you will be able to feel it. Again, I cannot stress this enough, Ground and Center.