This matter seems simple, but it will definitely consume a lot of time, because he cannot recklessly kill monsters without choices here. Doing so would not only waste his energy, but also trap him in an abyss of endless bad rewards. This is why he is currently using the power of ice to suppress the surrounding monsters rather than killing them all outright.
The second reason is that he temporarily gave up searching for powerful monsters here, choosing instead to return to Rogge Town to take revenge on a deceitful noble. This is also the quickest way to find out what's really going on with all he's experienced.
"There must be more elite monsters in Aifilan's ruins, and there should be more boss monsters like the dragon I encountered before. Staying here would surely yield considerable rewards... But I still have about five days, so there's no need to rush... So, Mr. Rogen, here I come!"
