What it is: A water-meets-oil formula that is instantly absorbed by skin and is like a concentrated multivitamin for your complexion. What it does: Concentrated like a serum by with the nourishment of an oil, this booster gives you the power to customize your skin care routine to meet your skin's ever-changing needs. Ideal for those experiencing sensitivity, it is formulated with cica, an herb traditionally used to help calm and soothe the skin.