I recently discovered that dying to a nightwalker (scion
callable mobile) results in a loss of experience.
My experience is rather limited, but as far as I know
dying to another player does not in general result in a
loss of experience, e.g. dying to a necromancer's pets.
I fail to see the difference between a cabal called
creature and a class called creature.

Is this by design or due to some technical stuff, say
nightwalkers being a special form of mob or something.

At any rate, I think it would be more fair if the killing
blow of a nightwalker of some scion didn't result in their
foe suffering loss of experience on top of everything else.