Obviously, none of the seven people on the ship with Klaus and Maud expected the god butcher to be Klaus's subordinate.
He is a legend.
In the vast universe, once a person reaches the Immortal stage, killing them becomes difficult. Just like what happened to Kilian, whose body was destroyed, yet he lived, Immortals can live only with their soul spirits.
Once they reach the Immortal stage, their soul spirits upgrade and become an Immortal soul. This makes them super strong and hard to kill.
To kill them, one needs powerful Immortal qi, powerful Immortal domains, and the right conditions to be able to kill them. If these conditions are not met, killing an Immortal is not easily achievable.
Their bodies can die, but their Immortal souls can escape and later reform their bodies. Of course, reforming a body after it is destroyed has some backlash on the warrior.
