D&D 5E FAMOUS LAST WORDS: "It wouldn't be here if we weren't supposed to fight it."

[Inchoroi]

Now that's interesting to me. Here's a serious question: Would you consider this dragon a part of the game, or is he window dressing? I ask because I suspect there's a very real psychological difference between "you've heard rumor of a dragon in the area" and "here's a random encounter with a dragon."

The dragon is included in the random encounter tables for that area--granted, its only a 1 out of 100 chance, but it does exist. In addition, the dragon has a standing bounty on his head, because he's taken over a gem mine that the city owns, and would very much like to have back. I wouldn't necessarily call him a "rumor", because the people who own the mine and the foreman are still alive and well and constantly try to recruit adventurers to go out and take the mine back, but none have succeeded, and few have survived.

They'd be behooved to go there, eventually, however, because there's a dangerous artifact that can only be melted in an ancient black's acidic blood.

 

[Imaculata]

In the very first session of my current campaign, I had a bunch of level 1 PC's fight a few level 1 prisonguards, and their pet crocodile. At first level a normal crocodile is a terrifying foe who can kill a first level character easily in one round. So I had the crocodile first rip one of the npc's to shreds, so the players were forewarned.

 

[Yaztromo]

I do put overpowred creatures sometimes in the adventures and they are there not to be fought but to be dealt with in other ways.
If you are a peasant farmer fighting with a spade and you face a demon or a castle-sized dragon, you should be clever enough to thing twice before charging.
Under this point of view, I do put super-overpowered creatures compared to the characters and plenty of warnings, so that it should be obvious enought that fighting is not the right choice.

 

[The_Gneech]

I try to create a "natural" world, and as such there are dangerous areas and not-so-dangerous areas. If my players wander into a dangerous area, they will encounter dangerous things!

But consider what "dangerous" means in this context: to a commoner with AC 10 and 5 hit points, an orc is just as "dangerous" as an ancient red dragon. So asking around at the local tavern isn't necessarily going to be useful for determining threat levels.

Some players, when told "There's a deadly monster down in that dungeon!" hear "This is a thing you're supposed to go fight!" Others hear "This is a thing you're supposed to run away from!" So that's not always useful either.

So at the end of the day, my general practice is "Put into the scenario what makes sense to be in the scenario. Make sure the players have an idea what they're up against, and let them decide what they want to do about it. Then let the dice fall where they may."

-The Gneech