The demigod undead that was revived and dubbed as The Reaper finally activated one of its more powerful skills. A domain skill is considered one of the peak skills not because it is difficult to get but rather its effect. The ability to change the terrain is something only those who have godlike blood possess.
Individuals who are said to have domain skills are often called as one who is closer to becoming a god. They are said to be closer to a god because they can change the very area that they walk upon which is described in the legends as blessed land.
Those who have domains are only called closer to a god because they can only change it for a moment unlike when a real god descends then the land itself will be transformed. The best example for this is what happened with the Silver Moore as it became a different area entirely. The whole terrain changed just because the twin gods descended even if the duration of their stay is short.