Small tavern adventure, does this work?

[Gnaritas]

Mind, english is not my native language, please excuse any misspellings or use of wrong words.

Your party enters a tavern, you appear to be their first guest. The barmaid welcomes you to sit as she is cleaning the tables.
<Innkeeper> Ah guests, are you hungry?
<Jim> Yes, we could use a meal, what are you serving?
<Innkeeper> I just got some mushrooms from the forest and am making a stew, will be done in a few minutes!

Not long after, the stew is served. The party starts to eat and 15 minutes pass.

The barmaid approaches the table, as suddenly she tries to push Jim from the chair. Jim throws fails a reflex save and falls on the floor. As you look at the barmaid she turned into a hag and as she lifts her hands the room is filled with some kind of gas that makes everything blurry and you since you failed your fortitude save, you are also nauseated. You attack the hag, but despite a good roll, you miss. The hag attacks, hits and you fail your fortitude save and all turns black. From the kitchen a Ogre joins the battle, the remaining party needs to deal with him too, but in the end, the Hag and Ogre manage to "kill" the whole party....

You give the party a minute to realise they have just been TPK-ed.

Then a bucket of water is thrown in your face, it's the innkeeper. It's the next morning and you are laying on the tavern floor after eating poisonous mushrooms the night before. The mushrooms made you hallucinatate and aggresive, but also very slow and weak. The innkeeper and barmaid tried to calm you down and forced you to the ground as you started to grow weaker. A healer came by but told the innkeeper it's fine and all will be fine the next morning.

Would this work out? Would i be able to convince the party the "fight" is real or is this just too obvious?

[weckar]

I just wonder how you will deal if the players DO make the saves or win the battle. Natural 20s are a thing.

[MrSandman]

I'm of the opinion that you generally shouldn't have scenes with predetermined outcomes in RPGs. If you really want to do it, I'd suggest briefly narrating the hallucination and moving on to the real adventure instead of trying to play it.

By the way, shouldn't the PCs get a save against the mushrooms anyway?

[St Fan]

Hallucinations / ordinary dreams are not usually played out. Now, a divinely inspired, prophetic dream, that's another thing entirely.

If such a thing happen, though, makes it SIGNIFICANT. Giving the PC a fake Total Party Kill for fun is not going to fly with the players, unless it happens to be an actual warning sent by a benevolent deity.

In which case, the dream may play out exactly like an encounter that you have actually planned, but you suspect to be overwhelming for an unsuspecting party. Like a very well-prepared ambush in a place that happens to be a dead magic zone.

Once the party is unfortunately wiped out, you can have them suddenly wake up from their bivouac the same morning (preferably screaming and flailing). The fact that they'd all have the same dream should easily convince them it was a divine vision (especially if there's an elf in the group, who did fell asleep and dreamed like the others when it shouldn't be possible for his race). Now forewarned of the exact nature, they can take precautions to avoid a repeat.

Heck, you can even do this retroactively if an encounter that you didn't expect to be deadly prove catastrophic for the party, erasing it as a prophetic dream. Don't abuse it, though; using it more than once would kill all tension for the players.

[pabelfly]

Have you ever played an unwinnable battle in an RPG that you've thought was fun afterwards? I haven't. It's a story that I haven't got any control over, and it's fundamentally unfair through mechanics I can't use or gross overlevelling compared to my characters.

[Saintheart]

Protip: don't do this to longtime Star Wars fans. Subverting expectations pointlessly triggers off their Rage (Ex) abilities.

[Thac0 Redeye]

The only way I'd do anything like this is if I over did my encounter and accidently caused a TPK. Then I'd have them wake up and have the "dream" be the work of the BBEG.