Trust me, you should rewatch the Elden Ring: Shadow of the Erdtree cinematic trailer after beating the expansion

Elden Ring: Shadow of the Erdtree's cinematic trailer dropped exactly a month before the expansion's release, and the collective response was about what you would expect: «This is rad, but I have no idea what's going on.» Now, though? Well I have kind of an idea what's going on after spending 80 hours or so in the DLC, and it's all about as grim and unsettling as you'd expect.

Spoilers for Shadow of the Erdtree ahead.

Right off the jump, we now know that the bloody gate of corpses Marika is hanging out around at the beginning of the trailer is the Divine Gate from Promised Consort Radahn's boss fight at the top of Enir Elim, only when we get there the bodies are calcified and bleached white by the ages⁠—in this primeval moment, the monument is still slick with gore and viscera.

Item descriptions and other tidbits from the DLC reveal that Marika came from a place called the Shaman Village, and that the hornsent society systematically rounded up the Shamans to butcher them and put them in great jars, making Marika's story, whatever her later excesses, one of revenge⁠—think what happens with Paul Atreides in Dune and you're pretty much there. 

My interpretation is that the jars were the prototypes or collected building materials for the Divine Gate, but Marika snuck past or tricked the hornsent to steal godly power from it⁠—possibly that golden thread she pulls out of a yonic flesh thing at the very beginning. One complication is that in-game, a lot of the petrified bodies around Radahn's arena have hornsent horns.

Erdtree map fragments: Uncover the Land of Shadow
Scadutree fragments: How to level up in Erdtree
Erdtree bosses: A full hit list for the DLC
Leda quest: Track the Erdtree main quest
Ansbach quest: Help the former servant of Mohg
Hornsent quest: Complete the quest for vengeance

The sequence of Messmer burning down Belurat has always been pretty straightforward, but as NewArtificialHuman points out on the Elden Ring subreddit, there is one moment that takes on a