Diablo 4 Season 9 spices up Nightmare Dungeons and revives a major boss

The fact that Blizzard is already showing off what's coming in Diablo 4 Season 9 gave me a bit of a jumpscare - time can't be zipping by that quickly, can it? Then I remembered that Season 8 was always meant to be an unusually short season. Consider my existential crisis halted, for now. It looks like it's going to be a spicy season as well, because alongside the usual influx of seasonal content, Nightmare Dungeons are getting some new features. Plus, a boss we slayed in Diablo 4's campaign is coming back with a vengeance.
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