The Black Mage and the Light Knight [Western Fantasy]

Liu Xi has crossed over, becoming the villainous character in a Western fantasy novel—a frail and cruel Marquis named Siyar, who is secretly a dark mage. His knight commander is the righteous paladin Langaros, who, after running him through with a sword, will become the male lead's brother and help him overthrow the Kingdom of Est. Now, the male lead is already on the path to overthrowing the rule, and his knight commander is about to discover that he is a dark mage. The paladin's sword is just one door away from running him through. Question: How to hide the dark magic circle in the room? Waiting online, urgent! Answer: Make the righteous paladin too afraid to enter. Siyar: I'm familia...