I recommend Mise en Scène Perfect Original Serum for damaged hair.

My hair is severely damaged from frequent bleaching and dyeing, so I always have to apply serum before drying it! It was always difficult to find a serum that made a noticeable difference in hair condition, so after trying several different products, I found that the Mise-en-scène Perfect Original Serum made the biggest difference, and I really felt my hair becoming softer! If you have damaged hair, I highly recommend giving it a try :)