It's unfortunate that much of fantasy fiction, videogames, and even a lot of pre-written adventures totally undermine this common-sense approach by slapping these "omen of doom"-type things all over entirely doable encounters, and presenting them almost as an incitement to adventure.When you hear rumors of a dragon circling a particular forest, or when sailors tell you that ships never return from a particular island, or when the guards remark that you "don't look strong enough" to handle whatever is inside The Howling Spire...those are called "hints" and you should listen to them.
It really does. I had to explain several times that "this ain't Skyrim" when they were rolling up characters, and I've written it a couple of times in the handouts and stuff. But I bet I'll still get angry emails after the first few games, about how monsters don't "belong in the game" unless the party can beat them.I suppose that might result in a certain period of... adjustment... when you work with new players!

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.