Source: Bestiary 3, pg(s). 33
Blood painters are eight-limbed creatures that follow a roughly bipedal structure. Blood painters walk primarily on their legs with additional support from two long arms growing from their midsection. A "normal" pair of arms extends from their shoulders, while a final set of two arms emerges from where their eyes might be expected to be. Those final two arms end in hands where the blood painter's eyes are set into the palms. Each of the upper eight limbs ends in a clawed humanoid hand.
The key ability of blood painters is to draw images with blood and bring the images to illusory life, at which point the blood painter can consume its creation for sustenance. These paintings can even be copies of itself, leading to a grim sort of quasi-autocannibalism. For the blood painter to draw these images, the blood must be freshly taken, and so blood painters have developed the ability to hold bleeding prey in thrall in order to collect a sufficient amount of blood.
When not hunting for blood, blood painters are obsessed with both the natural beauty of the world and manufactured beautiful art. Occasionally, an artist or dancer is able to trade their art for their lives, and blood painters guard these treasures with their lives.
One theory on the creation of blood painters, largely thought apocryphal, is that they arise from Shelynites who ceased eating or sleeping to focus on their art, ironically developing into an aberration who can only consume their own art.