Jacob was surprised by those words, 'Not only is this thing highly intelligent, but it also knows why I'm here and the purpose of this trial. Then it wanted me to form this contract before killing it? No, it's too risky; for all I know, it might be a trap to trick me.'
Jacob wouldn't listen to some unknown entity and form a contract with it just because it told him to. He knew better than anyone just how vast and mysterious the zodiac plains are and believing something unknown was the biggest mistake one could make in this place.
Like Immortika, he still couldn't completely trust it because too many things were hidden, and it was always the one in control. Adding another such existence was not something Jacob could handle. At least, in the cursed immortality case, he has some trust in its ability to grant him longevity and power.
