The Master Necromancer - Vol 1 - Chapter 71

Most of the damage done by the Ghoul Hunter by the Eye Ghost Creatures was inside damage; it was classical shock and blast damage, as the name of the ability suggests from the start.

From the outside, there is no damage done to the Ghoul Hunter, but because the Ghoul Hunter was the creature of Skraal and a directly summoned creature, he could easily see that the insides and organs of the Ghoul Hunter were damaged pretty badly.

This means this kind of creature is good against creatures with the human type of body; this means that if the creature they are fighting does not have strong skin armor to negate the effects of the ghost blast ability, they will be harmed from inside.

The humans could still use armor against these creatures, or the intelligent creatures can use armor too, but not natural creatures like Ghoul Hunter.