I'm not trying to be condescending in any way, but from your statements I can only deduce that you don't have a broad reaching spiritual education. This is not in and of itself a bad thing, only a sign of spiritual immaturity.
Lucid dreaming is an attempt to enter a transcendent state.
To be as brief as possibly, I'd like to point you in a particular direction and encourage you to do some research on your own. Consider this quote
The experience of being in a lucid dream clearly demonstrates the astonishing fact that the world we see is a construct of our minds. This concept, so elusive when sought in waking life, is the cornerstone of spiritual teachings. It forces us to look beyond everyday experience and ask, "If this is not real, what is?" Lucid dreaming, by so baldly baring a truth that many spend lives seeking, often triggers spiritual questioning in people who try it for far more mundane purposes. Not only does lucid dreaming lead to questioning the nature of reality, but for many it also has been a source of transcendent experience. Exalted and ecstatic states are common in lucid dreams.
The first statement of that paragraph is not reconcilable with Christian teachings.
As far as desiring to brutally kill something while in a dreamstate.....
A mental health expert might consider this to be an indication of anti social behavior or worse.
A spiritually aware person would tell you that there are consequences for those actions, even if acted on while in a dream state.
