TheBigHouse
Explorer
I'm considering leaving firebolt and chill touch as blue, but bringing the rest down one rank.
Please bit the black text! I'm with Legacy, can't read.
1.) Grim Touch is really better than some people think. The key observation: it gives you HP healing once per turn, not once per round. If you cast Evard's Black Tentacles for example, each creature affected takes 3d6 damage at the start of its turn, which means that if six orcs die in one round, you get 8 HP per orc = 48 HP total that round.
Can be abused with cagefuls of chickens (2 cp each) and Fire Shield to heal relatively large amounts of damage for cheap, even during combat. (Use your bonus action each turn to roll it over to another cageful of chickens.) Fighter 1/Necromancer X is surprisingly tanky already even without abusing Grim Touch--adding in cheap healing would make it even tankier.
Good Point.2.) Necromancer's Command Undead: if nothing else, you can Command one of your own ghouls created via Create Undead. Armor it up in plate armor and a shield and you'll have a nifty little minion with AC 20, 36+ HP (even more if you went the Inspired Leader route), and a paralyzing attack. Even better, Command a Wight that you created, and now you get not only your own up-armored Wight for free but also all of the zombies that it creates (which you can also armor). If you happen to luck into a Zombie Beholder (Int 3, one random paralyzing/fear/enervation/disintegration ray per turn) or a Mummy Lord (Int 11, essentially unkillable, spellcaster, high damage per turn and legendary actions that can damage, stun, blind, or prevent healing) you may have a tough decision to make about what to keep.
3.) Geas for Necromancers: when you create undead, normally you need to expend spell slots to keep control over them. Only, you don't necessarily need to do so. Geas V will charm a creature for 30 days (more at higher levels; permanently at 9th level) and force damage it for 5d10 once per day when it disobeys your instructions, which can be anything non-obviously suicidal. It's probably worth keeping most of your skeletons and zombies under your control just so you can command them telepathically with your bonus action, but for more expensive undead like Wights (which like skeletons are not immune to charm) it might be worth Geasing them to "follow my Wight Baldrick here and do whatever he does without harming anyone he does not attempt to harm". The wights can shrug off your Geas for 5d10 damage, but at least you know they can't harm you (because they're Charmed), and depending on how much Geas "hurts" to disobey they may be inclined to follow the Geas.
4.) Miscellaneous comment on Geas: it combos well with Dream. Geas will do 5d10 damage every day, Dream will (often) prevent that damage from healing. Net result: within several days, you have a dead target (traitor).
5.) Animate Objects and Darkness: if you have a party member who likes to use Darkness, like a Shadow Monk or a Warlock with Devil's Sight, it's worth bearing in mind that animated objects have Blindsight 30'. Within a darkened area they are even more murderously good than usual. Earth Elementals also have Tremorsense, which is basically the same thing.
6.) Planar Binding: even when you first get it at 5th level, Planar Binding is notable for removing the concentration requirement on spells. So at 9th level you could, for example, conjure an Earth Elemental, Planar Bind it for 24 hours (cost: 1000 gold), and then in combat use your concentration on Stinking Cloud to both obscure the elemental from its enemies (advantage on everything) and poison enemies (elemental is immune). At 9th level that's pretty pricey, and therefore niche, for something that only lasts 24 hours, but it scales rapidly. Totally worth considering even if you only want a couple of elementals.
7.) Mage armor doesn't require concentration and has a long duration. Consider putting it on anyone with a good Dex who is likely to take hits: a 2nd level Moon Druid in Giant Hyena Shape (AC 12 => 15); an air elemental (AC 15 => 18); an animated ghast (AC 13 => 16).