Deor is a Manga/Manhwa/Manhua in english language, Crime series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

The young prince, Deor, is an outcast in his own land. Born without the ability to use magius – a rare condition that marks him as an incompetent – he relies on his intelligence and tenacity to prove wrong those who believe he is not fit for the crown. However, with deadly demons and conspiracies threatening the very existence of humanity, Deor must protect the very kingdom which ridiculed him. Will he be able to defeat the demons and secure his position as king?