The Golden Crosses from the Shadow of the Erdtree story trailer have had their larger purpose in Elden Ring revealed: they're markers that represent the character Miquella's "footsteps," to quote an NPC, places where he sacrificed parts of himself for a greater cause - and more than that, they have some of the best items in the game waiting at their base.
Having attended a preview event for the upcoming Elden Ring DLC, we found several of these "golden crosses" scattered around the new Realm of Shadow - often near Sites of Grace - and interacting with them tells you about some element that Miquella chose to sacrifice there. More exciting for players, though, is that these crosses all had something called "Scadutree Fragments" just beneath them. I know that word looks like a misprint, but that's really what they're called - and they're incredibly important for the upcoming expansion's new leveling and difficulty system.
Scadutree Fragments can be redeemed at Sites of Grace for a blessing on your character that only applies in the DLC areas - a blessing that offers an across-the-board increase of the damage you deal and a reduction on the damage you take. As you find and spend more Fragments, you can make the Blessing even more potent and yourself even more powerful as a result. However, you can also choose to reset that blessing back to zero and get your fragments back at any time.
Basically, this is how you control the difficulty of SOTE, by spending Fragments until you reach a level of challenge and personal power that you're comfortable with… though, you have to actually find them first. Speaking personally, even plugging in every Scadutree Fragment I came across, I still found Shadow of the Erdtree suitably tough going. Very, very fun, but no less brutal than the base game.
Oh, and if you want to know why they have such an odd name… well, this is speculation, but the Realm of Shadow where the DLC takes place has its own giant tree, and some research tells me that "Scadu" is a word that can alternately mean "shadow," "ghost," "darkened area" or "reflection" in certain dialects of Old English.
It makes sense, considering that "Erdtree" and "Haligtree" roughly translate as "homeland tree" and "holy/sacred tree," respectively. Presumably then, these fragments are pieces of the larger tree that overlooks the Realm of Shadow - though what caused it to fragment are mysteries we'll have to find out when the full expansion launches on 21 June.