Upon reaching the tormented body of the basilisk, Vicente took advantage of the creature's weakness. He placed a seal of servitude on it, which could not be removed once it was magically solidified.
In the world of magic, magicians could tame creatures of other races or turn beings of their own race into servants. The terminology varied according to the type of race and the means used. However, the unilateral domination of one party, the master, over the other, the servant, involved basically the same principles, regardless of the means used.
When it came to taming beasts, it was done through a magical seal using the pentagrams or some other kind of special essence of the dominant being, the master.
By marking a weakened beast with the one-sided seal, anyone with enough power to maintain the seal could tame a wild creature and turn it into a tamed beast!