Karl began the work of deactivating the tower, so it was no longer considered an Immortal Rank magical item, and then began layering the extra runes that he wanted onto the stones of the tower, adding the extra functions to study and create mental puzzles.
Those were all fairly simple additions, as they were just changes to the options for the existing trials within the towers, and the change was as much about intent as it was about the actual runes.
But that was where things could get tricky.
If Rue didn't fully understand what Karl was trying to do with the tower, then there was a good chance that her upgrade attempt would fail, or she would only manage to upgrade a portion of the trial.
Though, even if she just upgraded the combat trials, that would likely be enough, as they were the only ones that involved dealing damage.
