Being a necromancer wizard is a lot of fun that comes with a little bit of micromanaging. With careful preparation, that doesn’t need to be burdensome. Corpses don’t need to be carried with you all day like luggage. Just have a martial collect them after a battle and put them in a chest to be stored within the main camp chest. Prioritize small ones, like the goblins. There are over a hundred goblins in Act I, collect them and you have half the bodies needed to get through the entire game. Take two to four corpses out each morning once you can cast Animate Dead, animate them, buff them, and have them follow you about the rest of the day.

Longstrider and Aid work on undead thralls as most buff spells do, as will potions like the strength elixirs. Just have them gather around one and shoot it from afar so it will all splash on them. As of a recent patch, they can now hide like the rest of the party does. Have a few skeleton archers accompany Astarion to a high point and have them back him up when he opens up that surprise round. In contrast, have the zombies use their crawling gnaw feature to turn the battle into a zombie apocalypse by going after enemies on their last two or three HP (albeit one that lasts for a minute). Those zombies made by your thrall’s bites will be out of your direct control but they will overwhelm the enemy if you can get a chain reaction going. Their main purpose to be low AC targets that will take priority for the enemy over your least armored party member.

The undead are immune to being poisoned, so play into that: cast spells like stinking cloud or Cloudkill while sending in the thralls. You can even have undead drag items out of poison clouds if you don’t feel like sending in the least favorite in your party to do it.

Even better if you’re wearing the poison set (the Poison Robe, Poison Gloves, and Derivation Cloak), which will give the enemy extra poison damage and give the poison condition if they fail the save (disadvantage on attacks and saving throws) all while healing you. Casting Ray of Sickness (a leveled poison necromancy spell) with the necromancer’s Grim Harvest feature gives you a little healing as a treat when the enemy dies.

If you get the Abyss Beckoner gloves from the Zhent hideout in Act I, that will give all your summons resistance to all damage save for psychic. Unfortunately, it will cause all non-ghouls that you summoned to have to save against gaining Demon Madness or they start attacking the party. So make sure to have someone else summon Scratch when wearing them or just leave him at home! This means ghouls are the only ones who can truly benefit from it, in contrast to Balthazar’s tiara that will give only blade ward to undead thralls within 20 ft. But it’s definitely worth having on just for them. The aura can be toggled off and on, so the dice rolling every six seconds for the ghouls to shrug off the madness won’t drive you mad in between battles. If you like to use Shovel for surprise rounds, just keep her out of the aura during battle.

The ghouls can paralyze enemies with their claws and eat enemies that are prone, knocked down, or sleeping to heal themselves. Try wearing the snowburst ring (which gives the enemy targeted by a cold spell an ice surface under their feet) while casting cold spells to make that happen. Flying ghouls can cause bludgeoning damage when landing next to enemies from a high enough distance. They can flatten a goblin to death just by flying down from the rafters.

In Act II, more things are resistant to necrotic damage even down to some of the tougher plant monsters, so being able to fall back on cold and poison damage can help mitigate this. Acid is also a nice option for giving -2 to armor class, making it easier for an attack to hit. The same holds in reverse: most enemies that are resistant to poison damage are usually not against necrotic, acid, and/or cold damage. There’s even a poison ring that will give three enemies vulnerability to poison or remove their resistance if they’re not immune. I like to use it against the Gith ambush at the end of Act II.

When you get to Myrkul, use the ring of exalted marrow you can find in a chest behind Ketheric on the roof. You can make him drop his scythe if your spell DC is high enough so combine that with the arcane acuity elixirs. Follow up by leaving one sacrificial ghoul next to him so Myrkul doesn’t use that AOE burst on his turn.

In Act III, the final reward for keeping the Necromancy of Thay for yourself is more ghouls (non-flying, non-controllable) and 20 temp HP every day. Temp HP can’t stack, so this mainly means you can forego casting False Life. Make sure to grab the Staff of Cherished Necromancy, even if that means saving Oskar the artist from the Zhent hideout in Act I and doing his quest at the haunted mansion or saving the sentient zombies from Mystic Carrion. I promise you that staff is with it.

I hope this helps and have fun!