"Wail of despair has double its former power, and they also get stunning touch. Wail of despair will allow for one move after use now. Banshees allow necromancer to go up against dreadnoughts."
-This buff is alot of extra power for this unit. I like your thought about the dreadnoughts and the stunning touch. The only thiing is letting them get an extra move after their double powered Wail of Despair means they will wreck the resistance of everything and then in the same turn be able to most likely stun. It just seems like alot in one turn. I think it would be more fair to keep those as separate turns so the opponent has a chance to counter that tactic.

"Scoundrels get resurgence and regen."- This is a low tier unit and you did already buff them so their sabotage can work on undead which I think is really interesting. You want to make them tougher with regen, ok. But resurgence for that tier along with everything else seems like alot for such a cheap unit compared to what other classes get. It also just feels like a strange ability for the rogue theme.
I do like that you gave some regen to the necro bone collector. I can see it match their scavenger theme and also necros really suffer too much from lack of battle recovery so thanks on that score!