In order to turn into a Blood Servant, a person's appearance had to change into something that resembled a Blood Clan member. Their skin became a morbid white color, in which one could see the blue veins and arteries clearly. It wasn't limited to this alone, as all the hair on a person's body would fall away. So, even if their mouths remained the same, they would be bald and have no eyebrows. However, it was obvious that the three Blood Servants didn't care about their outward appearances and instead were intoxicated by how much their power had increased.
The prince was an example of this. His eyes shone brightly with excitement. He had been beaten up by Jiang Chen, and now he had finally gotten a chance to avenge himself and give an outlet to his anger.
Jiang Chen obviously couldn't manage to face these three guys, who were more powerful than low-grade Spirit Emperors, alone, without the help of his magical clones. He also had other ideas about how to defeat them.