A method of forming an airfoil, includes forming a hybrid skin core, a tip flag core, and a trailing edge core. The hybrid skin core, tip flag core, and trailing edge core are connected to form a first core portion. A leading edge core and a serpentine core are formed. The first core portion, the leading edge core, and the serpentine core are assembled together to form an airfoil core. An airfoil is formed around the airfoil core.