Is Eyeshadow Primer/Shadow Base necessary ?
Eyeshadow primer/base are always only an option. If you have eyelids that are oily or your eyeshadow tends to crease throughout the day, the primer/base slows the rate of creasing. Some eyeshadow primers also tend to intensify the color of the eyeshadow. Between UD and Too Faced, I've used both and are both good. No specific preference.