A practitioner asks: “Reiki is a popular energetic therapy available to many at low cost. In what ways and to what extent might a Reiki treatment be augmented by praying that the Reiki be directed to such issues as malignant cells, deep subconscious trauma, negative cordings, or retrocausal healing? Can Reiki energy be effective on these and other causes of illness identified by GetWisdom?”

You are wanting to mix apples and oranges here. While Reiki is considered a divine energy, that might be or might not be, depending on what is truly being formed within the practitioner in the way of intention. We see this as wanting to put the cart before the horse. To be as effective as the Lightworker Healing Protocol and Deep Subconscious Mind Reset, a Reiki practitioner would, in effect, have to conduct the protocols as intended because it is the intention of the divine to carry out the requests that makes it effective, things like retrocausal healing, the management of cordings and thought form corruption, and so forth. Most Reiki practitioners are really using their own energy and not that of the divine. What is important to accomplish the deep karmic repair done by the LHP and DSMR, is knowledgeable intention, not healing power per se. The healing capability, energetically, of humans is of minor significance in the scheme of things. When deep and lasting healing gains are made, it is when there is a human-divine partnership through human requesting divine intervention in an effective fashion through creating the needed intention and its level of specificity to direct the divine realm in doing what is truly most important. While the Reiki practitioner could borrow specific requests and set an intention for them to be carried out, it is the whole of the protocols designed as an integrated system of healing that bring about their true power and effectiveness. So cherry-picking a subset of techniques and attempting to launch them by Reiki practitioners would be a much less effective approach. So while your scenario you ask about is well-meaning, it would be unlikely to add anything of value compared to learning to do the protocols and executing them as done across the board by the majority of practitioners who are not invoking any other special energy.