Definitely want more enemy repositioning skills, preferably ones that depend more on your own position than teleport (like how Gust would require you to be in the right place to move your enemies where you want them to go.)
*Necromancer: Pain Link
Think Shackles of Pain but instead of the target receiving the damage that you take it will link two enemies together and they will take damage when the other is damaged
Agree with Rat, that's very strong. Just splitting the damage between the two is a neat idea, and very versatile. I also like it linking together certain debuffs or buffs, though that could be stupidly strong with CC (especially something like charm). Maybe it just links statuses that damage, like bleeding, burning, poisoned?
Another similar skill could be a debuff that makes any characters 5m or so from the debuffed target take 30-50% of the damage the debuffed target takes. Maybe something like "Hateful Empathy" or "Suffering Circle." Maybe could be tied to blood, where enemies (or all characters) standing in the same blood puddles share some damage, though I do think maybe there's already a lot of blood-focused Necro skills.
Necro also needs corpse-manipulating skills for the most thematic skills. Corpse Explosion is an obvious one (probably a 3-mem skill) that could damage and disease nearby characters (maybe letting you automatically loot* the items in the process). Raised dead from corpses is also obvious, though not sure if Summoning Master is the only summon tree. Raised dead could be very weak summons that you can't directly control, perhaps.
*On that note, a "Loot Magnet" skill would be neat, where you loot all nearby corpses and items on the ground for 1 AP. Would be a nice telekinesis skill, if that tree will have any skills. Could prove useful for gaining some consumables mid battle, though might be pretty situational and maybe would need something else to make it worth the memory cost.