According to Slayer's Hearts intel, there were been thousands of Skeleton Dragons and vampires flying in the Death Valley's skies as they spoke. Naturally, there were also hundreds of thousands of lowly cannon-fodder specters roaming aimlessly in the valley, accompanied by Spectral Bosses. And of course, at the end of the line, stood their main targets—the six Liches and two Spectral Shamans. If they could achieve that, they stood to earn over 800 Honor Points.
All in all, they could have netted a whopping 6000 Honor Points taking out this Undead Stronghold. This was the very reason why Qin Ruo set his eyes on the Death Valley, making it the first place for their three-clan alliance to attack.
Yes, it was indeed very difficult to take out all six Liches. However, Qin Ruo came prepared.