Necromancer build

[Godwoken Dovahkiin]

Haven't played this game since the PS3 days back in 2013. I really like necromancers thanks to Diablo 2. Is there any way to make a viable necromancer build that will take on Nightmare? Reading through all the mage spells so far I think it's best to focus on Spirit and Entropy, though that seems really lackluster in terms of damage. Any insight on must have spells or spells that complement the playstyle?

So far what I got in mind:

Animate Undead tree
Arcane Tree
Most of Entropy
Spell Might
Glyph of Paralysis

Spell Combos:
Advanced Reanimation
Entropic Death
Improved Drain
Nightmare

Blood Mage + Spirit Healer or Shapeshifter

[Jondar Korric]

since no one ever bothered to respond: I'd ditch Glyph of Paralysis for Paralyze->Mass Paralyze and go Spirit Healer+Blood Mage (then into Battlemage if you take the character into Awakening)