These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Black Legion
Ass Pull: The Fall of Medusa V campaign is one. Ygethmor, the Black Legion sorcerer whose death was the primary objective for the Space Marines, was killed by the Eldar, but since the Space Marines the Series Mascot, they were awarded the "moral victory" for completing the most objectives.
Memetic Mutation: "Abaddon has no arms". Taken from a picture of Abaddon without his arms, to further emphasis his uselessness.
Moral Event Horizon: In the Emperor's eyes, when Horus killed the Custodes/Imperial Fist/Ollanius Pius with a single look, he realized that his son was beyond saving.