The ilaw is performed when somebody gets sick after cutting a tree. It is believed that the illness was caused by a spirit in the tree whose permission was not asked before the tree was cut. Old coins, rice wine, tobacco, lime, betel nut and leaf are brought by the mambunong to the place where the tree was cut and offered to the ampasit.
Illness is believed to be caused by nature spirits and ancestor spirits that must be propitiated through ritual offerings. A pig is butchered for a sick person and a mambunong inspects the bile. If it looks shiny and healthy, this means that the spirits are satisfied with the offering. If not, another pig is butchered until the mambunong says that the spirit is satisfied.