In the beginning, Jake could still track the movements of his companions using his mental sense. But before long, they seemed to vanish, as if ripped from his mental grasp. Somewhere along the constricting neck of the funnel was a Faraday cage, aimed not at electric fields but spiritual energy, that scrambled his perceptions, disrupting and dispersing the mental energy he had forcefully engaged.
If he were closer, he could have undoubtedly maintained control of his spiritual energy. Yet, with the interference of the barrier and the introduction of this psychic Faraday cage, it became an intricate jigsaw puzzle. Despite his persistence, he managed to project his mental sense slightly further, but as the difficulty exponentially increased, he had no choice but to abandon the attempt.
"From now on, you're on your own," Jake didn't forget to warn his three companions before his connection with them was completely severed.