The Rooks can be improved. This increases their levels, adds new archetypes. It has 3 categories that you can improve the rooks with: Ringleader, Insider and Swindler. Across those categories you will find the 40 skills that improve the Rooks.
Subcategories
This category has the following 3 subcategories, out of 3 total.
Pages in category "Assassins Creed Syndicate Gang Upgrades"
The following 39 pages are in this category, out of 39 total.