I got bored and decided to do this since this is my dream dual class.
I would pick Necromancer/Sorcerer Magicka for the ultimate Daedric Lich experience.
I also note these are ones I would pick and not use them all at once.
Necromancer
Ricochet Skull - Basic Spammable of the Necro and love the skull. I do like Crystal Fragments but Ricochet Skull fits more with a Lich playthrough.
Stalking Blastbones - Create a skeleton to chase people and create a necrotic explosion. Pretty basic and really terrifying that a exploading skeleton is coming right towards you.
Mystic Siphon - Using a corpses last energy to create a necrotic field that hurts enemies near it.
Necrotic Potency - Siphon the corpses life energy to heal yourself while building up points for the ultimate skill. Makes sense since most Liches steals life essence of people to increase their own power.
Enduring Undeath - Makes an area that heals you based on the amount of corpses. Pretty effective and looks like a ritual spell but also visuals look awesome.
Spirit Guardian - Summon a wraith to heal you while transferring damage from you to it. I use it all the time because I love wraiths and the healing/shield is awesome.
Skeletal Arcanist - I use this but I would like to use Scamp Familiar unless we can have Skeletal Mystic model or Skeletal Defiler model as alternates like the Stone Slate skin for Warden Bear.
Sorcerer
Haunting Curse - Pretty fitting for a lich and to make sure the prey won't survive without major damage. Also I love the visuals of this spell.
Shattering Prison or Rune Cage - The crystals are Black Soul gems which stop the enemy in their tracks. First one is just a cluster of Black Soul gems on the ground while 2nd is a sphere with black soul gems floating around. I like them both but I probably prefer Rune Cage since makes the target really helpes and the black soul gems makes it look like the target is being weakened by them.
Dark Conversion - Liches have no need for physical attack nor running so trading it for Magicka and Health to make the battle turn in their favor would make sense. I have to mention it also uses Black Soul Gems for the spell and I love the visual.
Hardened Ward or Bound Aegis - Either one is fine but depends which one blocks the most damage. Visuals are nice and I prefer these 2 over the Bone armor because I do like summoning skeleton creatures but don't like wearing them since feels to Primal for me like Reachmen.
Daedric Tomb This one is better then minefield because as a Lich I doubt anyone would go near you so I would use that against them. Also this would go nicely with Stalking bones because if you time it right you can cause a enemy to go towards the runes while the Blastbones are being conjured.
Volatile Familiar First thing is I do like the Skeletal Arcanist but I like Scamps. Nothing much to say here since its just a DPS pet, Though I will have to say we need customization for the pets. Would love to make my Skeleton Arcanist use the Skeletal Mystic model or Skeletal Defiler model. If they do that then I will move back to Skeletal Arcanist unless they have Mind Shriven Scamp skin for the Familiar
Ultimates
Glacial Colossus - Tbh I wish it was a Bone Colossus or the original Bone dragon Ult. Nothing against Flesh Atronachs but I just like the ones from Oblivion Shivering Isles more.
Animate Blastbones I use this alot ironically just because I liek summoning 3 skeletons just to bombard an enemy.
Suppression Field Only Sorcerer Ult I like because it makes the enemy helpess and prevents them from using magic. I actually only really use the Destro Staff Ult, Mage's Guild Ult, And Animate Blastbones Ult.
Well thats what Dual Class I would use and all the Skills I would use from both sides. So if Dual Class was a thing, What skills would you use from both classes?