The HD Elixir came with the HD Travel Kit I bought. I definitely would not buy this on it's own. The elixir is similar to a primer. The primer is already moisturising enough for me so I have no use for it especially in the summer. I also use moisturiser after I wash my face.
The elixir comes with an eye dropper tool and you take a bit and drop it onto areas on your face that seem dry.
Since I have it, might as well save it and use it for winter.