achloryn This is probably generic advice for any necro, but it seems like late-game personal survivability comes with ward - and other than making sure you have 70+ in resistances, that's basically it. So you end up sacrificing minion damage in gloves / boots / helm / offhand, but you can end up with over 2k ward with only a couple of good items, and eventually over 3k. It works well with Necros having Int as their primary stat, and access to several ward passives, like Reclamation of Souls and some stuff in the Warlock tree. At the same time, your damage will eventually drop off until you make the switch to Dread Shade, probably instead of summon skeleton (skeleton archers and warriors can't hang late-game anyway). But again: all of this is really beyond the scope of your guide, which is totally fine!
Also, I have a suggestion for your guide: for Wraiths, I ended up using Twin Spirits (with Sequel of Avarice) instead of Delay the End and I liked it much better, if nothing else just for the mana savings. I found I couldn't keep zombies going while also summoning wraiths constantly, and having two static wraiths was just as good if not better anyway.
And I wouldn't sleep on Giant Zombie for zombies, either: it doesn't reduce how many you can have, only their cost, and they can do so much more.
Anyway thanks again for the great guide!