When used as a base it intensifies the color of any shadow applied over it & makes the eyeshadow shade true to color on the skin (see pictures below) also increasing the lasting power of your eye look.The pencil is made with a blend of mineral oil & powder, so is creamy & easily blended into the skin, my preferred method of application is to draw & cover my eyelid with the pencil & use my ring finger to blend into the skin.
Here are some swatches of some random shadows to show the intensity of them when used with 'Milk'
Top - Plain shadow
Bottom - With Milk as a base