Derik couldn't help but frown while gazing at Lucien. His instincts told him to kill this kid kept getting stronger the more he realized how much of a threat Lucien is to him. The reason why it took him so long when using the devour to consume the Phoenix flames is that the Phoenix flames had a life of their own and it could resist hid devour ability to a certain level. It was this same Phoenix flames that prevented him from healing when he fought Emperor Fei and reduced his so-called immortal body to ashes!
Gaining this ability, Lucien has become more of a threat than ever. While Derik possessed absolute, mysterious powers, Lucien possessed the most firepower amongst them. Making it possible for him to overwhelm Derik.