So, for the past several months I have been playing a 13th-level necromancer in 5E. I've always been a necromancer fan, and was happy to find so much support in the core rules; I also wanted to see if a horde of skeleton archers was as powerful in play as it looks on paper (because on paper it looks crazy-broken). It's true that 5E has reinstated the old "good wizards don't use animate dead" thing, but I solved that issue by the simple expedient of making my necromancer evil. Some people were curious to hear how it played out; here's my experience. YMMV, of course.
Overall, I find a high-level wizard is extremely versatile, with a seemingly bottomless bag of tricks. My go-to spells are fireball, which is top-notch both as a weapon and as an incendiary device, and dimension door, which is endlessly useful on the battlefield, particularly when the enemy is far away and the melee warriors are having trouble getting there. I also get a lot of value out of seeming, stinking cloud, and cloudkill.
The skeletons: When you can bring their full power to bear on an enemy, a big force of skeleton archers is horrifyingly effective. But that hardly ever happens. Even with necromancer bonus hit points, skeletons drop like flies in high-level combats and there are seldom enough corpses at hand to replace more than a few. Plus they quickly overload your capacity for teleportation magic, they don't work well in cramped spaces, and you have to keep seeming up at all times if you want to stroll around town with 'em. And every time you teleport out and leave them behind, you have to go to town and buy a heap of bows and arrows to arm the next batch. It's a great illustration of the difference between theorycrafting and actual play.
That isn't to say skeletons are useless! Far from it. A small group of skeletons (such that you can take them with you on a teleport, and if they all die, you can replace them from the corpses of your enemies) is not hard to sustain, and they contribute substantially even at high levels. It works out pretty well.
Synergy with your minions and fellow PCs is huge. Cloudkill and stinking cloud are must-have spells if your party includes people highly resistant to poison, like undead and dwarves proficient in Con saves. In addition, having another caster along lets you pull off some nice combos. Nothing like having the bard hit an enemy with Otto's irresistible dance right before you disintegrate. And of course there's the ol' cloudkill/forcecage one-two, which is a lot more effective when you can do it in a single round.
TL;DR version, 5E necromancers are solid but not overpowered. They are more effective as "wizard with a few skeleton minions" than "Army of Darkness."
Overall, I find a high-level wizard is extremely versatile, with a seemingly bottomless bag of tricks. My go-to spells are fireball, which is top-notch both as a weapon and as an incendiary device, and dimension door, which is endlessly useful on the battlefield, particularly when the enemy is far away and the melee warriors are having trouble getting there. I also get a lot of value out of seeming, stinking cloud, and cloudkill.
The skeletons: When you can bring their full power to bear on an enemy, a big force of skeleton archers is horrifyingly effective. But that hardly ever happens. Even with necromancer bonus hit points, skeletons drop like flies in high-level combats and there are seldom enough corpses at hand to replace more than a few. Plus they quickly overload your capacity for teleportation magic, they don't work well in cramped spaces, and you have to keep seeming up at all times if you want to stroll around town with 'em. And every time you teleport out and leave them behind, you have to go to town and buy a heap of bows and arrows to arm the next batch. It's a great illustration of the difference between theorycrafting and actual play.
That isn't to say skeletons are useless! Far from it. A small group of skeletons (such that you can take them with you on a teleport, and if they all die, you can replace them from the corpses of your enemies) is not hard to sustain, and they contribute substantially even at high levels. It works out pretty well.
Synergy with your minions and fellow PCs is huge. Cloudkill and stinking cloud are must-have spells if your party includes people highly resistant to poison, like undead and dwarves proficient in Con saves. In addition, having another caster along lets you pull off some nice combos. Nothing like having the bard hit an enemy with Otto's irresistible dance right before you disintegrate. And of course there's the ol' cloudkill/forcecage one-two, which is a lot more effective when you can do it in a single round.
TL;DR version, 5E necromancers are solid but not overpowered. They are more effective as "wizard with a few skeleton minions" than "Army of Darkness."