The aura is a reflection of a creature's true nature. It emanates for all living creature and is invisible to most. Some elves can alter their vision to see auras. It is also believed that the aura can sometimes be felt. For example, chills may be felt when a murderer enters an establishment, or a child who stops crying in the presence of a healer of Mitra.
The colour and nature of an aura is determined by the morals and actions of its host. The aura never lies.
In their simplest forms, good auras are seen as white and bad auras as black. With more advanced techniques, wisps of green, brown and blue can be seen as mixing with the white for good auras, while traces of red, orange and yellow interlace with the black for bad auras. These wisps move around the creatures, their movement more erratic with stronger auras.