We've seven appendices in this book, each of which is intended to help the GM run her Crimson Throne game, or to expand it beyond the scope of the adventures as written.
Appendix 1: Continuing the Campaign
This short appendix suggests seven additional plots that can be expanded by you, the GM, to continue your Crimson Throne game, including one variant that sees Ileosa come back as a vampire! (And yes, of course we gave you art of vampire Ileosa!)
Appendix 2: Korvosa and Beyond
The adventures themselves present all the information about Korvosa you'll need to run encounters key to Crimson Throne's plot, but as in any urban game, your PCs will wander. This appendix presents a detailed gazetteer of Korvosa as it exists under Ileosa's rule, and serves as an expansion to the original Guide to Korvosa we published long ago. While owning that book will certainly help you run a Crimson Throne campaign, I strived to include enough information in this appendix that it's not necessary. In addition to all sorts of adventure hooks and location descriptions for the city, this appendix presents multiple city stat blocks for Korvosa as it undergoes numerous changes during the course of the campaign (from a healthy city to one on the edge of anarchy to one in the grips of a plague to one under martial law). Nearly three pages of rumor tables will help you drop hints to your players to foreshadow upcoming events, and advice on places where the PCs can rest and recuperate, shop for magic, or secure spellcasting services rounds the appendix out, along with some additional notes on the surrounding lands (including the Cinderlands themselves).
Appendix 3: The Harrow
The Harrow has always held a powerful role in Curse of the Crimson Throne, and this appendix not only provides you advice on how to use Harrow readings in your game and a mechanic for the PCs to use those harrow readings to influence fate, but also includes a list of what every single card in the Harrow deck symbolizes in the context of Curse of the Crimson Throne, so that when you pull a card during a reading, you'll know precisely what that card means for the PCs and their destiny.
Appendix 4: Blood and Pain
This short chapter is a sort of catch-all—here you've got rules for the plague that wracks Korvosa, but also rules for a kyton eidolon subtype. Why the subtype? Well, in the original version of the Adventure Path, we had an NPC named Shadowcount Sial, who had levels in a prestige class called "thaumaturgist"—a class that allowed a character to gain the services of an extraplanar minion. This prestige class, alas, was not one we updated into the Pathfinder rules, and while I initially toyed with doing so in this book, I settled on something better. I translated Shadowcount Sial into an unchained summoner, which gave me the perfect opportunity to give rules for kyton eidolons—something that there was no room to include in Pathfinder Unchained but which I know many folks have been asking for!
Appendix 5: Equipment and Magic
There's a few new items of equipment and many more new magic items to be found in this campaign—and they're all presented in this appendix. While some of these are updates from the original campaign (such as the third eye, Zellara's Harrow Deck, or the Crown of Fangs itself), others are brand new or have been quantified as items for the first time, including full details on the Everdawn Pool and rules for the strange poison known as "fool's leprosy" that Ileosa uses on her husband!
Appendix 6: NPC Codex
Curse of the Crimson Throne relies heavily on its NPCs, be they villains or allies. This appendix begins with an index that lists all of the significant NPCs in the adventure, along with their role and the page number you can find their stats on. But the meat of this appendix are the twelve significant NPCs presented in two-page formats. Here's where you'll find information on key NPCs like Laori Vaus, Blackjack, and Ileosa herself, along with a few newcomers—we've included statistics for Kazavon himself, for example, in case your PCs are unfortunate enough to let the mighty blue dragon come back to life! Many of these NPC entries include additional rules options utilized by these characters, such as new spells or feats—and if the PCs play their cards right, they'll be able to learn these new options from NPCs they encounter!
Appendix 7: Bestiary
Finally, we've got the bestiary. Here, we've provided several random encounter tables for you to roll up wandering monsters to spice up play, but have also presented full stat blocks for several new monsters: the soul-powered akaruzug, the tragic chained spirit, the malevolent danse macabre, the immense and alien havero, the plucky house drake, the pain-infused pharmakos, the lumbering red reaver, and two types of vermin that infest the city of Korvosa: drain spiders and dream spiders.