AMNATSHI
The pigment used for the color-changing tattoos of The People is made from a cuttlefish-like creature called the Amnatshi. Its application requires the concentrated, dried powder of the ink diluted in a ceremonial emollient which contains a number of plants… Judging by the smell of the mixture, I’d guess these botanical compounds provide a form of low-grade anesthetic (the tattoo application is “old school” with needles, after all) as well as acting as a disinfectant to prevent infection.
Not much is known of the Amnatshi, nor the properties of its ink. Our guess is the ink reacts to the electrochemical signals (or chemicals released while experiencing certain emotions) which not only make the ink visible (it is usually invisible, leaving only the skin’s natural tone unblemished), but affects the color of its appearance as well.
The Battle Lords who are blessed by Dagda have the powder directly applied to their skin. By what process the original ink is removed (given its permanence) or the new design takes hold is, as with many things of Turas, unknown.