Nice touch!
That let's me value the Scions actively spreading haunted lands, as on a philosiphical quest...
Like the elves spreading the forests, not only bacause it makes them powerful, but also because that's how they want the world to be!
D'Tesh shouldn't be bothered by such a trivial task, they don't want a place where life and death mingle. Total dominion is their goal, if I'm correct, and the broken wasteland they leave behind a (more or less wanted...) side effect of their methods.
...And that, incidentally, leaves a niche open for a D'Tesh minor leader that actually spreads Haunted lands (actively, maybe recieves a creeper each x turns). Sort of a schismatic (ahem...sp?) one, could be the lesser evil of the D'Teshi bunch.
But this is obviously modmodders ground, because clearly Valk won't introduce such a leader
PS: Really looking forward to new D'tesh. Untill now I avoided playing with them, even if I already love the flavour, because I want to approach the more polished version that's in store