From publisher blurb:
The darkness grows deeper and your enemies are stronger than ever. Use your newfound powers to fight back, but you must never forget what really matters... The Advanced Rulebook is the first supplement to the Double Cross role-playing game. Both player and Game Master will have access to new abilities and items, making characters more unique than before.
The Advanced Rulebook is the first supplement for the Double Cross game. It introduces new mechanics like the following:
By sacrificing one of your Lois slots, you acquire a special ability that distinguishes your character. While these abilities are powerful, the loss of a Lois slot means that you are more likely to lose your character.
Exhausted Loises are traits that can make enemies more menacing. While some are only for the purpose of roleplay, there are plenty of abilities that can make battles much more intense.
In addition, game lore is also expanded on. Many historical events and characters are introduced, giving the GM more material to use for stories.