Hello, i like the conjurer in Grim dawn , and the fact the game has built in pet damage shows it was planned ahead, not like Witch Doctor who had awful pets when D3 was first released.
But globally, i have never seen a hack and and slash with a class that could control more minions than the necromancer in Diablo 2. I remmber it was possible, with skeletons, revives and the golem, to get about 60+ monsters.
Sometimes the game crahsed online, but other than that it was very fun.
Would it be impossible in 2016 to make such a class, because ai would be too hard to code, it would demand too many resources, or be hard to balance?
When i saw the order of Death Vigil, i thought," one day this could be the base for an add-on adding a new class, the necromancer".
Well I’ve been using a build very similar to this one which gives you a small army of bugs, ghosts, extraplanar dogs, and so forth. It’s pretty fun. Then there’s also The Lazy Pokemon Master build, which I hear great things about. So yeah, pet builds are alive and well in grim dawn. Shockingly, in a post-apocalyptic setting it’s a great thing to have a portable strike force on hand at all times. 
There are mods with necromancer masteries you know, 3 different ones have been released!
Well yeah, many mods in games offer a necromancer class(there is even a necromancer class with that mod for diablo 1), i use the lazy pokémon master build myself and its pretty cool. Its just that in terms of raw numbers, not many games let you control as many mobs as the necromancer class in d2.
I think that with the lazy pokémon build you can control a maximum of nine regular monsters(the crow, te briathorn, the hell hound,the yeti,the undead from shield, the primal spirit, and the three monsters from wand.