The mods for Crusader Kings 2 are just as good as the game itself. So when of CK2's best mods gets even better, it's a very good day indeed.
There's plenty of great storylines to tell in CK2, but one of the best is Warcraft: Guardians of Azeroth. It's a mod that makes the four great races of Warcraft playable in Paradox's grand regicide simulator, replacing small nations and tribes with things like murlocs, gnolls, kobolds and pygmies.
Over the year, the developers have been busy adding bits and pieces from Warcraft lore into the game, like magocracy as a form of government and hashing out the mechanics for the Scourge.
The latest introduction to the Warcraft simulator: the Burning Crusade, or more specifically, the influence of demonic magic known as Fel.
Fel works in a similar manner to corruption from the Total War games: over time, a province will become more infested, the populace will start to die, they'll pay less taxes, and characters in the region will slowly turn to the dark side.
What's more interesting, however, is that you can help launch the Burning Crusade yourself. Any player that gets to the Tomb of the Dark Titan can opt to sacrifice themselves, transforming into the Fallen Titan and granting them the power to summon non-stop armies of demons.
You can still kick off the Legion invasion if part of the Fallen Titan's soul is gone, although you'll need a powerful artefact (like Gul'Dan's skull) or a powerful source of magic (like the Sunwell). It's almost a bit like Total War: Warhammer's central campaign mechanic, but you can swap sides mid-campaign to join the Burning Legion rather than being locked into your chosen path from the start.
There's no official release date for Guardians of Azeroth, although the developers have publicly stressed that a build will be pushed out "soon". You can follow the developers and ask questions in the official Discord channel, or their ModDB page.