The idea is to mainly Haunt/Locust Swarm, and use Grasp of the Dead and Horrify to keep the enemies at bay, ideally staying on the move and not having to cast too often only using Locust Swam and occasional Haunts that don't spread, using Soul Harvest and Spirit Walk to keep health up due to Blood Ritual.
The main concerns are, it won't be enough damage to efficiently take out groups of enemies, even with the Resentful Spirit runed Haunt. Using the Alabaster rune on Haunt also gave me another worry, since its duration is now so low, that enemies wouldn't reliably die with it active to go to a new target, resulting in excessive use of Haunt.
With Pierce the Veil, I wasn't sure whether to rune Soul Harvest for returning Mana or Health, but I decided on Health for now. I'm also not totally set on Spirit Walk.
Basically I'm toying around with going for runes that maximize the Haunt/Insect Swarm duration, while adding an additional attacking skill, replacing potentially Spirit Walk. If I remove the Alabaster rune from Haunt, it could be used as a Mana regaining possibility if it is an issue.
Anyway, what are your thoughts?