The opening dungeon to BG3 is far far more DnD than what the opening of BG1 was. "Oh no I got to see lots of evil things"
You don't actually fight the Mind Flayers, you fight some weakened Intellect Devours, Imps and Thralls. The devils fight the mind flayers.
The Intellect Devours are somewhat nerfed, they aren't as dangerous as in MM, but homebrew monsters are a thing, especially when you want a setting, and I don't think Body Thief makes sense to use on someone with a tadpole.
I really don't get this "it doesn't make sense" argument. It's a cool "setting the scene" for the plot going forward. And I have no idea why it "hates casters" to be on a "spelljammer ship" since it doesn't seem to affect the gameplay at all.
I think it's a perfectly viable first level dungeon, when it's part of a 1-10 campaign where Mind Flayers are the big threat (it seems)
That spell you linked isn't an official spell, so why the heck do you expect Larian to include it? They are using mostly Players Handbook Rules.
Conjuring things is a 3rd level or higher spell in official rules.
