Got this 15mL deluxe sample of
DDF Amplifying Elixir from the
Ulta Spring 2012 GWP and been using it for the past month. This is a serum and is supposed to go on after toner but before moisturizers. It's supposed to help the skin absorb whatever goes on next, maximizing its benefits.
Spring 2012 GWP

***Screenshot via
Ulta.com.