Far as I think about it, if one wants to hide a spell, they should pick up the subtle spell-metamagic. Making every caster able to do what is supposed to be a special ability (on par with doubling the range/duration of a spell) cheapens the ability and makes casters even stronger than they already are.

If he doesn’t know what spell you’re casting, that means that he’s even more likely to assume that you are trying to cast an harmful spell, making him attack you. And casting a spell takes an action, basically a third of your turn if you want, so the hobgoblin has at least 2 seconds to react, if not more. And thats plenty of time to stop himself from jumping.

Fortunes Favor doesn’t seem like the optimal spell to use in a situation like this (even if you could). Unless the games include no social component, enhance ability would be better.

About the house rule: I get why you’d use the rule for simplicity, but especially if your not playing a cleric, but instead a wizard or an artificer, it seems weird to make the PC a chosen one by having those spells.

I usually give NPCs a set selection of spells they use. But this set is only their prepared spell-list, it varies depending on the NPC and most preparation-casters will have access to the other spells on their list, should the need arise (as it most likely won’t, so there is no extra work on my part).

Not to worry. The Zenths tend to be pretty chill.

Ah yes. Good ol’ Volo. Nice to see him from time to time. I should use his books more often.

Casting a spell and holding it uses visible components the hobgoblin could react to.

Incite greed also explicitly says that the creature avoids obvious harm while approaching you and does nothing beyond approaching you. If the would always run after the gem (forsaking personal safety to do so), this would be noted in the description.

They could also just make different adventures in different parts of the Faerun. But they’d have to actually update they’re lore then.

Thats funny, because I’ve seen some DMs where nobody cares wether or not lvl. 10, they still treat you as if you were lvl. one and don’t know sh*t about you. (Mainly in campaigns where the characters travel a lot. I still find it weird. Rumors spread quickly.)

Ironically enough, I’ve had campaigns where just doing what the priestess suggested would have been a better solution than what the party ended up deciding to do.

Probably. An author once wrote this piece of conversation:

“Wait? You can transform matter. Thats magic.” “Your people can use metal to fly over buildings.” “Of course they can. It makes perfect sense.”

Having a world, where “magic” actually exist raises a lot of questions about some conventional expressions and cultural aspects.