The Inspector by Larz is without exaggeration the single most important tool in the dominions community. This is true to the newest noob, the oldest vet, the casual player, the modder, everyone. It has the stats of every unit, spell, item, site, and event all taken straight from the source code. It is very accurate and kept up to date. It even has every single sprite in the game available for download for modders.
LucidTactics produced a video on how to use the advanced feature of the Inspector. https://youtu.be/ytItMjdszHw
list issues and inaccuracies: map move, gold costs, ???