D&D 5E Surprise and Sneak Attack

[Ovinomancer]

He's a 5th level Fighter with 50 odd hit points (who only dies at 0 HP when 50 or more damage remains, or he fails 3 death saves).

The assassin needs to:

1) Hit the Fighter (with advantage most likely) against the Fighters AC. Likely but not certain.
2) Deal enough damage to kill the fighter against those HP, or at least reduce the Fighter to 0 HP in order to finish the job off once he's at 0 HP. Not certain.

The outcome of a hostile action against a PC (or anyone for that matter) is almost never 'certain'. Unless we're dealing with an NPC that can 'auto hit' somehow and 'auto kill' with the amount of damage he deals against the PCs HP, it's not certain. Not even close to certain.

It's good that you acknowledge that you'd rule this situation having uncertainties and therefore use the resolution mechanics. That's a valid approach.

Equally valid, however, is deciding that a sleeping target unaware of the assassin is going to have a hard time living with two feet of steel through the ear and that, given the target is sleeping and unaware of the assassins positioning the blade, that uncertainty isn't part of the equation. Really, the only issues here are how this situations is obtained. I'd never do this to a PC with an NPC because, well, frankly I have infinite dragons and don't need to be a jerk and abuse the game to fiat this into existence. I'd definitely let a PC do this to an NPC, but they'd have to pass all of the necessary checks to get there first.. I don't see the need to add a combat at the end of a careful approach full of successful checks. If the PC has already earned getting into that position, I'm quite okay with thinking that things aren't uncertain anymore. I think that this needs to be looked at as well, rather than just postulating a jerk GM being magically stymied by a strict application of the combat rules. The GM's still a jerk, and that won't stop them.

 

[jmartkdr2]

Compare to what the Thief gets at 3rd level.

I mean the Assassin is already getting advantage on the 1st round of every combat against creatures that havent acted yet. Thats pretty awesome on its own.

An autocritting ability? I mean that's gnarly as heck man. It should be hard to pull off.

Personally I just give my assasins 3+ levels of Gloomstalker ranger. +Wis to Initiative, invisibility in Darkness, great spells (pass without trace, hunters mark), darkvision, and extra movement AND attack in the 1st round of combat, that deals extra damage (all likely with advantage and autocritting thanks to Assassin).

Add in Alert, and your Assassin is a killing machine who never goes last.

Yeah, the gloomstalker is a better assassin than the assassin in most campaigns.

I get limiting how often you can Assassinate - reliably getting it as-written every combat would be way too much. But it's instead limited by needing a lot of luck, which is an un-fun way to gate the use of an ability, or a lot of system mastery, which is against the design of the rest of 5e.

If it was easier to achieve, it would either need a per day (or similar) limitation or to be toned down in overall power.

 

[Cap'n Kobold]

In my opinion the case of a single assasin attacking a single completely unaware target from hiding is definitely a situation where following the initiative and surprise rules can give a very counter-intuitive result, and my solution is simple; don't roll initiative. The assassin goes first and gets to make his attack. If the target is still alive after that, combat proceeeds normally.

So: you have someone (Mr Mook) hidden behind a corner with a knife as a single, completely unaware* target (Mr Lee) approaches it.
(*Mookie's Stealth has beaten Bruce's perception.)

Does Mr Mook get to automatically go first and make their attack? Or is there even a slight chance that they're going to wake up stuffed into a skip without even finishing their fist swing?

You may be confused by the way the D&D round treats actions as instantaneous, even if they take up the full 6 seconds. The initiative rules represent the chance that someone fast enough can react to a person going for a knife and hit them before they start stabbing.
Remember it is the "going for a knife" that everyone is reacting to even though by the round structure, that only resolves at the same time as the "stabbing".

(It is possible to to come up with edge cases (completely invisible/silenced/undetectable attacker shooting an invisible and silenced projectile at an unsuspecting target) where you may need to adjudicate a different result. That is perfectly fine.)

 

[Flamestrike]

You can always narrate away rules nonsense, but I prefer not to. It's the wrong way to use narration IMO.

Hit Points.

 

[Flamestrike]

It's good that you acknowledge that you'd rule this situation having uncertainties and therefore use the resolution mechanics.

Better than throwing the rule book away for no reason like you do.

Equally valid, however, is deciding that a sleeping target unaware of the assassin is going to have a hard time living with two feet of steel through the ear,

He doesnt have 2 feet of steel through his ear according to the rules.

The DM determines surprise. The positioning. Then initiative is rolled, and turns taken in order.

 

[Swarmkeeper]

Better than throwing the rule book away for no reason like you do.

He doesnt have 2 feet of steel through his ear according to the rules.

The DM determines surprise. The positioning. Then initiative is rolled, and turns taken in order.

I'm not @Ovinomancer, but I play much like he does. And we're not "throwing away the rule book away for no reason". We're actually reading the books completely and applying as much as we can to ensure everyone has a good time and memorable stories are made. Of course, there are many ways to have fun with this game.

How to Play (PHB p6)

1. The DM describes the environment. The DM tells the players where their adventurers are and what's around them, presenting the basic scope of options that present themselves (how many doors lead out of a room, what's on a table, who's in the tavern, and so on).

2. The players describe what they want to do. Sometimes one player speaks for the whole party, saying, "We'll take the east door," for example. Other times, different adventurers do different things: one adventurer might search a treasure chest while a second examines an esoteric symbol engraved on a wall and a third keeps watch for monsters. The players don't need to take turns, but the DM listens to every player and decides how to resolve those actions.

Sometimes, resolving a task is easy. If an adventurer wants to walk across a room and open a door, the DM might just say that the door opens and describe what lies beyond. But the door might be locked, the floor might hide a deadly trap, or some other circumstance might make it challenging for an adventurer to complete a task. In those cases, the DM decides what happens, often relying on the roll of a die to determine the results of an action.

3. The DM narrates the results of the adventurers' actions. Describing the results often leads to another decision point, which brings the flow of the game right back to step 1.

This pattern holds whether the adventurers are cautiously exploring a ruin, talking to a devious prince, or locked in mortal combat against a mighty dragon.

In certain situations, particularly combat, the action is more structured and the players (and DM) do take turns choosing and resolving actions. But most of the time, play is fluid and flexible, adapting to the circumstances of the adventure.

Often the action of an adventure takes place in the imagination of the players and DM, relying on the DM's verbal descriptions to set the scene. Some DMs like to use music, art, or recorded sound effects to help set the mood, and many players and DMs alike adopt different voices for the various adventurers, monsters, and other characters they play in the game. Sometimes, a DM might lay out a map and use tokens or miniature figures to represent each creature involved in a scene to help the players keep track of where everyone is.

It's all right there. "Sometimes, resolving the task is easy." Like when a PC wants to off a sleeping NPC mook, for instance. You don't need to invoke combat rules for any and all attacks. You can if you want. But it is absolutely not mandatory. And I would argue it can actually be contrary to the ultimate goals of the game if you do. I've been there - for example, 4+ years ago in my early days of DMing 5e when I told my 10 yo son to roll for an attack when his 5th level Assassin was trying to off an unsuspecting solo goblin guard. It wasn't fun to make him roll in retrospect and he said as much. We play, we learn, we improve, we have more fun.

 

[Campbell]

Models are not perfect. Sometimes they break down. Using a set of mechanics designed for skirmishes between small numbers of aware and active combatants in cases where it does a disservice to the fiction is silly.

I would prefer the game handle this stuff seamlessly, but it does not. Many games allow you to handle trivial combats with a single check or no check at all.

 

[Flamestrike]

I'm not @Ovinomancer, but I play much like he does. And we're not "throwing away the rule book away for no reason".

You're ruling 'insta-death' in a situation clearly covered by the rules.

This deprives Fighters and other martials of their core class feature of extra Luck (represented by their higher HP and HD) for absolutely no good reason.

 

[Flamestrike]

It's all right there.

You missed this bit:

In certain situations, particularly combat, the action is more structured and the players (and DM) do take turns choosing and resolving actions. But most of the time, play is fluid and flexible, adapting to the circumstances of the adventure.

Someone seeking to do harm on someone else is combat. It's structured for a reason. By arbitrarily ignoring those rules, and that structure you're deliberately punishing classes and characters that are good in combat, and have made choices based on that structure.

Might as well implement fumble rules and watch fighters start disembowelling themselves every turn, when they're not getting insta-killed in their sleep (no roll required!) by lowly assassins or just being insta-killed from falls of course.

 

[Asisreo]

I'm not @Ovinomancer, but I play much like he does. And we're not "throwing away the rule book away for no reason". We're actually reading the books completely and applying as much as we can to ensure everyone has a good time and memorable stories are made. Of course, there are many ways to have fun with this game.

If I was playing a game and fighting an enemy, then I cast a spell to out that enemy to sleep, do I get to end combat early?

If I cast the sleep spell on a BBEG (no save) and use subtle metamagic to prevent counterspelling, do I get to win since we can kill him in one strike? If I can, I will. Not even trying to metagame, in real life, I would absolutely slit people's throats by forcing them to sleep if I was mortally opposed to them.

I agree we can skip the whole combat part if there isn't a chance they'd live within the rules. If you have a commoner sleeping vs a Level 20 PC, no need to roll initiative. It's basically impossible for them to survive.

If we're talking about a sleeping ancient red dragon, they get their autocrits, their deadly strike damage if the dragon fails, their sneak attack. But they do not instantly kill the ancient dragon.

I think this is fair.