Seclusion [1]
Damien honestly thought it would be an easy time. It would be time-consuming, sure, but in practice, it was nothing more than sitting down and comprehending a concept, something he'd done countless times before.
However, what he thought was not the reality of the situation. When it came down to it, there was more in store for him than a boring time alone in a dark place.
Damien spent several weeks trying to interpolate the concept of "revival" into a facet of his own power. With his knowledge of Samsara, finding the root of revival was actually relatively simple. Once he put his mind to it, he had no trouble theorizing about how it could be achieved.
However, he still needed to gain a foundational understanding of what Nonexistence truly was.
In short, he had to bring that which did not exist into the light so he could conquer it.
That was just as hard as it sounded.