Situ wanted to attract the underworld creatures to attack him and collect their energy cores in the process, to make a massive transformation!
He was sure that with sufficient time, he could accomplish this, but to expedite the process, energy cores were the most effective way.
He had to attract more creatures to attack him, and perhaps he could accomplish this faster. As for why he didn't go searching for them, it was simple: he was being cautious.
To put it in another way, he was afraid, as he had no idea what lay in this underworld his spirit had been thrust into by the Taixun Demon Sutra he practiced.
He was just sure this Underworld was far from straightforward, and before he had accumulated enough strength, moving around was foolish.
He was certain his current strength didn't even rival a newly advanced Heaven Mandate realm.
With such a situation, running around was nothing short of foolish and seeking death.
