The Reginnaglar Ceremony (Adelheid #2)

Worthiness isn't given but taken.

After her twelfth birthday, Adelheid von Vuldar, must take the next step for her ascension to the throne, the Reginnaglar Ceremony. For generations, members of the imperial family have tested their mettle in dungeons to prove their abilities, and now, it's Adelheid's turn. Leading her fledging band of knights, Adelheid must delve deep into the Byrgir Dungeon and shorten her distance to the throne.

But as Adelheid soon discovers, monsters are far from the worst dangers within the dungeon.