So they streamed some of the new stuff and I skimmed through the video cause it was super long and not very scripted so pretty annoying but anyway, in short:
There's 3 endgame scenarios like before, the End Times with Archaon leading, Vermintide with Thanquol and the Nagash one.
When the events start(you can pick which one you want, and you can pick multiple if you want to do them, one after the other though not all at the same time, default start turn is 80-120 but you can adjust it up to 200), every faction related will instantly confederate(so all Chaos with Archaon etc), while every other faction gets diplomacy bonuses with each other. The endgame armies can now devastate the land, which effectively remove the regions from being useable until you clear the endgame and also gives them a win state(if too much of the world is devastated you just lose, even if you yourself are still alive). This is visually represented in the world with the lands being changed, destroyed and corrupted so it looks quite neat. There's a variety of objectives to do before you can win, basically kill enough stuff and collect things then do a final battle. The difficulty of the final battle depends on how much you've been doing during the event, ranging from impossible if you haven't been doing shit(Archaon's army starts with 100% ward save for example) to probably rather easy if you have.
After that they showed a bit of Archaon's campaign itself and it looks better with the ability to confederate every chaos armies(including demons and norsca) and such. Then when you achieve short victory, you get a prompt to start the endgame with you as the actual endgame threat(you can refuse if you don't want to do it and presumably if you've picked another endgame it'll start later instead). You get to go around devastating the land(can't do anything but raze in fact) and you get stronger as you do and win if you devastate enough. Now it's kinda unclear if you can do this with Nagash and they apparently mentionned you can't with Thanquol, so still not sure how these will be handled when played. Because their mechanics are weirder I could see both not being available, like Vermintide constantly spawns free armies everywhere the undercity reaches and all Skaven units are doubled in unit count so as the player it'd be a bit broken.
Bunch of other smaller stuff but better wait for patch notes/official write up anyway. Overall looks quite good though.
