D&D 5e

And that's kinda a shitty situation to put a PC in. It's like how no one likes Save or Die, except this is a mundane version of it that often has very hefty penalties.

>How would you make an assassin as a main enemy a credible threat then?

Make them not a useless foe once the guy does actually wake up? There is an entire martial art style that works great for assassins (Murderous Shadows), as it's mostly about 'Concealing your presence so the other guy can't find you' (Giving you a hefty bonus to dodging and toughness as it's much harder to lay a solid blow on you).

It's a martial arts game, if someone wants to kill someone of note it's going to end up with a fight of some sort .

Don't be afraid to drop players to 0 hit points (in such systems). Most systems have some manner of lifeline for PCs that are "killed" to be saved. Maybe it's a First Aid roll to stabilize them. Or death saves. Or the "negative hitpoints = CON means death" thing, so the bleed out for a bit. There are very few games that are so deadly as to just flat kill someone when their health goes to zero, and if you ARE playing a system like that, then you and your players know what you are in for, and you should act accordingly. PCs make enemies, and the tone of the system and game dictates how they act. In a D&D-alike? They grandstand and threaten with theatrics. Players can get laid low to zero health, but there's always a chance to save them, and most times that's more than enough to put the fear of god into them. So don't be scared to do it.

In your situation, sure, sneak in and stab them. They're at 0 HP now, making death saves. The noise alerts the watcher. The watcher chases off the assassin while waking others. Roll a death save. Healer or someone able tends to the dying. Death save. Skill roll. There are ample ways to deal with such a problem, so the PC is likely not in any REAL danger, but it sure as shit feels like it. But yeah, be careful about how you apply assassins; you need to balance them being dangerous and competent with being stoppable within the PCs' means.

Are we talking about D&D 5e still?

Also, the issue is an assassin typically works best 1 v 1. But if the other party members join in after the person wakes up, then they'll just trounce the assassin.

If the assassin is strong enough to fight the entire party at once, they aren't an assassin anymore. Why bother being sneaky if you're that strong?

Still, maybe that could be a good idea, if there was a way to isolate the player and make it a 1 on 1 fight.

>Are we talking about D&D 5e still?

No, I was talking about how assassins are handled in a DIFFERENT game as a comparison. Hence saying LOTW.

Just because someone can react to the first attack doesn't mean the enemy has instantly stopped being credible. A fight while wounded, unarmored, and unarmed can be scary as hell.

You could also add on complications like lingering wounds, poison, items being stolen, ect. that make the situation more than just "I won a fight, everything is back to normal again."

Good idea! A slow acting poison... it would put pressure on them over the long term but give them time to act. Assuming they fight off the assassin.

Sure, just make sure it's not a poison the cleric or druid can handwave away with a level 2 or 3 spell. Make it more involved than that. Find an alchemist or something who can MAYBE treat it but needs a rare herb or something and then send the party out on a mini-quest against the clock for it.

That's true... Paladins can heal any poison or disease just like that. I don't think there are poisons immune to that?

As a DM, thats when you say it's a MAGICAL poison (because WTF isn't magical in DnD... ugh) or do like the people in are discussing and limit what healing magic is actually capable of.