Perhaps the Necromancy class can have an abillity to turn 1 person into stone for a short durration? Maybe he can summon a sircle of sharp bones in an AOE around himself to damage other players?

I think Necromancer should be able to resurrect for a while after receiving lethal damage but resurrect as a ghost warrior or as a shadow warrior and fight for 5 to 10 seconds, and then die. Necromancer should use illness and diseases because dead bodies rot and spread disease. Also Necromancer should be a summoner of undead creatures that instead of summoning one pet indefinitely it should summon many pets for short amount  of time, and dealing great damage means keeping maximum number of summons as much time as possible (pets like zombies, skeletons, etc.). It would be great if necromancer have mechanics with the summoned pets (maybe while pets are fighting or with the bodies they leave when die), something like explode a body and create diseases and stun, consume a body and restore health, consume a body and buff the party (including pets), consume a pet to summon a better creature, etc.  

Remember not to confuse witch with necromancer, necromancer use necrotic magic, while witches use demonic magic. In other words necromancer plays with dead elements while witch sell her soul to a demon and use element taken from hell.

I will propose 3 specializations, 2 dps caster and 1 dps mele.

Dps caster full dmg: Summoning creatures and while they are active use shadow damage spells. ( maybe frost spells to slow)

Dps caster sticker: Diseasses and prejudices, damage over time and being able to take out some small creature

Dps mele: A mixture of the above, being able to take out small creatures, some damage over time spell and shadow damage abilities for the sword and frost to slow

Hello, Diablo Immortal just was released, and the Necro skills look nice, you can check them for a bit of inspiration, I like the concept.

They have 3 "specs" (you can combine Skills however you want) pets, AoE corpses and Support/Tank. 

Yes I'm already level 51 xd