This looks exactly like the type of build you’re seeking.
If you’re worried about it being too tailored to end-game, I’ve been playing a Necro who’s using Spirit Plague and Harvest for damage alongside the Mage Death Knights and I’ve just past Chapter 8 with little issue. I’ve died a few times due to being reckless, but Spirit Plague is a great leveling skill now that it has the “add 1 spell damage for every point of INT” node.