The first time they had tried using the zombies' crystal hearts as a way to get stronger faster since they were everywhere, the gains they had gotten from it were significant to their strength increase.
Though the quality of the zombies' crystal hearts was significantly lesser than that of the monsters, their quantity could make up for it.
While they were still a considerable threat, their threat could be somewhat controlled to a certain extent, unlike that of the few mutated life forms they encountered.
Those were the true monsters.
At least zombies had no extra ability that was bordering on the supernatural, or so most people in the world currently thought.
Considering the matter related to increasing their strength, Malachi and David, being both imaginative big thinkers, have also considered the possibility of encountering difficulties in increasing their strength as they got stronger.
