Thought it might be good to start a thread to discuss the upcoming patch in detail! Please do not post any leaks in this thread!
https://www.youtube.com/watch?v=O9hvag2z_QU
I'm thinking that the voice toward the end of the trailer is the Warrior of Darkness, I think we might see his return this patch. He seems to mention an upcoming calamity, which lines up with a lot of people's theories about the expansion colour schemes (ARR = Morning, HW = Day, SB = Evening, 5.0 = Night).
I suspect we are going to be heading into the 8th Umbral Era. Instead of stalling the upcoming calamity we may have to let it happen, as the light may be overwhelming the first shard again, and the only way to prevent that happening is a calamity. This could also explain why Varis is in league with the Ascians, he could be aware of the massive imbalance between light and dark, and sees that the only way to prevent it is to work with Elidibus.