With extreme perception, Jacob completely focused on his pinky finger and the blood in it. Using the cursed heart, he turned the blood in his finger into countless blood threads!
The skin around his pinky finger suddenly turned bright red, and Jacob felt cold chills just by turning his blood into threads. From the second blood glyph, he had learned to control the life force and magic force within the blood, and he found that these two were the key to the Cursed Bone Marrow Amalgamation!
Without any control over the life force, he couldn't spread the blood into extremely thin fibers, and without the magic force, sculpting them on his bones was just a pipe dream.
Furthermore, his cursed blood was different. It was filled with extremely powerful life force and an unknown magic force, which were very similar to his hex mana but far more potent. So, he needed even more control to manipulate it.