That's what they say, but this "Godslaying Spear" as a supposed trump card actually doesn't give Ling Xiao the ability to turn the tables in a desperate situation.
It might even be tough to use this thing to go down with the enemy.
Without other "sacrificial offerings," even if Ling Xiao drained himself completely, its lethality might not even kill a ghostly entity—a rough estimate from Sun Hang suggests it could at best take down a single terracotta soldier.
These soldiers, made from red crystal, aren't high in memetic strength. If pitted one-on-one against a ghost controlled by Zhong Ling, even the weakest ghost could easily overpower the soldier.
As for concentrating a large number of "live sacrifices" for "offering"... that's just Sun Hang's conception, but in practical terms, how to concentrate a large amount of life force onto Ling Xiao is an unsolvable problem to begin with.
Even putting ethics aside, there are still insurmountable technical limitations.
