So what in the writings of Marx do you feel advocates totalitarianism and/or mass death?
That is twisting it - Socialism/Communism ultimately is an attempt to brute force past the inadequacies of human nature, eventually you reach the point (due to the problems of reconciling between individuals under those principles) that for them to be successful you have to resort to Totalitarianism it isn't something that is advocated in the writings of Marx, etc. but an unfortunately reality that can be seen time and time again in history.