Die for Our Ship: Aggra gets a fair amount of this. This is not surprising, since her debut sinks the Thrall/Jaina ship, but it still comes off as quite vindictive.
Moral Event Horizon: Magatha poisoning Garrosh's axe Gorehowl, which results in Cairne's death and is immediately followed by her having the Grimtotem kill her enemies and take control of Thunder Bluff, nearly costing Baine his life.
Never Live It Down: Garrosh will carry the burden of killing Cairne for the rest of his days, no matter how grey and ambiguous the affair was.
Nightmare Fuel: How the night elf sentinels describe how their companions were not only killed, but skinned and chopped into pieces.
Tear Jerker: The aftermath of an earthquake in Kharanos, which claims the lives of many people, including one of Anduin's friends. Cairne's funeral, especially considering that his long-time friend Thrall Never Got to Say Goodbye.
Values Dissonance: In-universe. Jaina's theory on why Thrall is unable to denounce the attacks on the night elves as strongly as Varian thinks he should is that orc culture does not allow it.