Source: Borne by the Sun's Grace, pg(s). 88
A calaca resembles a large, grey skeleton that stands six feet tall and weighs 40 pounds. It dresses head to toe in fine clothing and accessories to conceal its true nature. Each calaca carries a musical instrument (typically a guitar or fiddle) that allows it to play music, but the instrument can be destroyed on purpose to unleash a powerful sonic blast. Calacas also always carry an antique weapon (usually a sword or pistol with one single bullet), whose purpose is unknown even to the calaca itself; when asked, the calaca will say that it was gifted by the gods.
Calacas typically arrive at the door of the deceased's widow, widower, or next of kin, claiming to be a friend or admirer of the parted; or they show up with food and drink during the deceased's funeral, as long as doing so would not be disruptive or insulting. As they play songs that celebrate the deceased's life, they try to learn about that person and their loved ones, so they might better tailor their consolations to each individual; as they cannot speak to the dead or use enchantment, they must rely on mundane conversations.
Most calacas do feel the sympathy that they express to those whom the dead left behind, but this grief does not come from loss, but from the pain that mortals will never understand the beauty and necessity of death, and they express this sorrow in music and laughter. If forced to fight, calacas typically retreat.
The calaca's role is to dissuade the dead's loved ones from trying to bring them back via unnatural means; they use persuasion to do this, never magic or trickery. Calacas often achieve this objective by convincing them that death is simply a second chapter of life, and if they cannot do so, they call upon psychopomps better suited to the threat.
Calacas typically target the rich and powerful, those with the means to bring the dead back to unlife. In difficult cases with multiple dead people, calacas band together as troupes and throw elaborate feasts, where each calaca plays a different instrument or part in the show. These extravaganzas can last for days if the need warrants and the calacas' disguises hold. They are sometimes joined by catrinas, whose abilities complement those of calacas by calming the grieving. When not performing their duty, calacas assist other psychopomps journeying to the Material Plane.
Calacas typically report to nosois, who record the details about their encounters. They occasionally visit and soften a target set to be assassinated by a morrigna, or play dirges to maintain the ranks of vanths marching into battle.