(Spoilers)
Upon completing a 100%, 807/807 caught Pokedex in Pokemon Reborn, you receive a special item, that being the Ebony Stonepiece. This item unlocks the door in Citae Astrae, and plays a special cutscene about Lin, and how her history with Arceus essentially started. All by the power of a marshmallow.
I ended up doing a living dex, on the Anna route. It was 100% worth doing. Best 190 hours spent in Pokemon by far.
![](https://i.ytimg.com/vi/EehevXlhF4Q/maxresdefault.jpg)