Conscience is the good part of your soul that says something is moral or immoral.
What is the bad part of the soul which tempts to do bad actions?
I don't believe we have a word for such a thing.
A conscience is either well-developed or poorly-developed or somewhere in between. It is not a "good" part which has a counterpart that is "bad."
Catholic Christians believe that we suffer from a damage called Original Sin that hinders our ability to choose good all the time. We are flawed. We give in to temptation.
The thing which causes us to do bad actions is our imperfect, flawed human nature.