Drawing Shadow Using the "Multiply" Blending Mode

Add shadow using a layer whose [Blending mode] is set to [Multiply]. The content drawn on the [Multiply] layer is multiplied by the color value on the layer below to create a darker color, making this mode ideal for adding shadow. If the color on the layer below is pure white, there is no change to the color. The darker the color on the layer below, the darker the color that is created relative to the layer below.