"Obsidian Tower" is a frequent project title for players of sandbox and RPG games:

: The story is set in the castle of Gloamingard, which houses a mysterious black tower containing a door that must never be opened.

: When an accidental death occurs near the sealed door, Ryx inadvertently breaks the ancient seal, risking the release of a world-ending threat.

Will You Make it to The Obsidian Tower? - SETTLER OF THE BOARDS

If you are looking for content related to the 2020 high-fantasy novel,

: Ryx , the granddaughter of a powerful ruler, possesses a "broken" magic that kills any living thing she touches.

: You can find a detailed character and plot refresher on the author's official website. 2. Gaming: Builds and Dungeons