A thorough, logical and lovingly developed guide to really expand the game. It adds flavor and morality to both in-campaign and between campaign life for your players. The one addition I made for our table was a CR based XP table to go along with it.

The only thing I wish there was in addition was a Foundry/Forge/roll20 module so that I didn't have to create every harvestable and item by hand. Well worth it for what it brings to the game!