Nothing, he just won't be afraid to die. This method, by the way, was done very often. People who were terminally ill could not cope with the thought that they would soon die, and under LSD it was much easier to do this, so they quietly left for the next world. Also, for cluster headaches (sooo severe pains), LSD was given, it helped to get rid of this pain, and when used for some time, it generally healed people
With your permission, I will cite an excerpt from the book "LSD is my problem child" by Albert Hoffman, the man who synthesized LSD.
" This practice arose from the observation in American clinics that especially severe painful conditions of cancer patients, which are no longer relieved by conventional pain relievers, can be alleviated or eliminated altogether with LSD. Of course, this does not mean an analgesic effect in the true sense. pain occurs, rather, because LSD patients are so separated from their bodies that physical pain no longer penetrates their consciousness.In order for LSD to be effective in such cases, it is especially important that the patient is prepared and instructed about the nature this experience and the changes that await it.In many cases it has proven useful to pre the clergyman or therapist guided the patient's thoughts in a religious direction. Numerous cases tell of patients who, on their deathbed, gained important insights about life and death, freed from pain, in LSD ecstasy, resigned to their fate, they met their earthly end calmly and without fear. The knowledge gained so far about the use of LSD in terminally ill patients has been summarized and published by S. Grof and J. Halifax in their book The Man in the Face of Death (E. P. Dutton, New York, 1977). The authors, together with E. Cast, S. Cohen and V.A. Pahnke, were among the first to study this use of LSD. "
This is useless, because there is an endogenous psychedelic DMT that is many times stronger than LSD. DMT is secreted in a person's lungs when they are about to die. Nature made sure that it would be pleasant to die. So if you have a dying person and LSD, then leave him alive.