I'm completely obsessed with this product from Chanel (Multi-use illuminating base, £33 - Selfridges). My mum introduced me to it at the start of summer and it completely changed the way I apply make up. (I should mention that I changed my make up to Chanel in June as the Mac I was using previously clogged my skin which isn't ideal for summer.) 

The fluid does everything from creating an even skin tone before applying foundation, to adding a natural glow to your skin.

Since it is multi use, I've used it in a number of ways so far and it hasn't faulted. It's been mixed in with my foundation, used as a primer, mixed with Chanel's Les Beiges fluid as well as their Sheer Illuminating Fluid and each time the results for my make up are perfect. Even if I choose to not wear make up somedays, I still use it as a moisturiser as it reduces the redness in my skin, is lightweight and, like I said, gives it a natural glow. 

I think this will become one of my staples, despite the price, but the best thing is that you only need to use a small amount so it lasts for ages.