He originally intended to use the same tactic, lying in wait around the village and ambushing the next group of Cooper Clan cultivators. However, the Cooper Clan wasn't stupid and their Clan Leader was also very self-aware. He knew that in the eyes of the villagers, he was seen as a "Master" but in the Cultivation World, his strength was barely worth mentioning.
However, the Cooper Clan had extensive connections, and the Clan Leader immediately personally reached out and invited a "Grandmaster" from the Third Great Boundary to come to their aid. He also had several younger generations from the Cooper Clan follow, pretending to be another group sent by the clan to investigate the situation.
Walter was deceived and burst out from his hiding spot, only to be killed on the spot by the Third Great Boundary cultivator.
