Some of this is denomination dependent but the mass torture of people in hell for all eternity would seem to fit what I was saying. Then there is also much of the Old Testament where God is either directly responsible for intentionally indiscriminate genocide including children and infants (e.g. the flood & killing Egypt's first born sons) or commands people to commit genocide in his name +/- mass rape of the survivors (Balaam, Amalek, Babylon etc).
I acknowledge that mass torture of people for eternity would fit your statement, but as you acknowledged, that is "denomination dependent" and not necessarily defining of either the Bible or Christianity. The earliest Christians had no such doctrine, and it's rather absent from the Bible. It took a couple hundred years for such to be grafted in from the Greek and pagan religions, adding assumptions that humans are naturally immortal (whereas the Book itself says that we are mortal and shall die), and so forth. I'll simply say that true Christianity obtains no such doctrine from the Bible.
If you are considering the question of whether God is unjust for when he chooses to kill people, you need to also consider this in the light that he is the reason anyone has life to begin with. The same God that creates us also has the right to destroy us if necessary. But besides that, he has also said that he will bring the dead back to life. For consistency's sake, if you were to fault God for deciding when someone would die, you might as well fault him for making man mortal in the first place, or taking away the Tree of Life which granted continued life. God isn't under the obligation to give mankind immortality, especially considering the evil man has proven himself capable of.
Your last description is inaccurate. There are no commands from God to commit mass rape. Slaughter of peoples, or even an entire race of people like the Amalekites, but that again goes back to the fact that God, as the creator of mankind, and the giver of life, has the right to say when people shall die and when he shall raise them again. If you allow for God to exist in the first place (which you must allow in order for your criticism to have a chance to find a target) then you have to allow that he is as the Bible describes in those ways, as well.
If you kill someone, you have taken something that does not belong to you. You had no right over their life, and you are unable to undo what you have done. If God kills someone, he is the reason that they were alive in the first place, that life belongs to him, and he is going to speak to him directly when he raises him in that next moment. That same God has the power and ability to heal age, disease, mental deficiency, harm, and trauma... even ignorance and stupidity. The damage we inherited from this world that we chose for ourselves six thousand years ago when we would not have God rule over us can be fixed.
Just to put this in perspective, according to Evolution Theory, I would have the perfect right to kill whomever I wanted whenever I please, or to show any amount of cruelty to any degree capable. Nothing matters as long as I produce viable offspring.