Instakill Mechanics in TTRPGs

[GraveDev]

I have been working on a TTRPG of my own (who hasn't?), and one interesting hurdle I bumped into was how to make the rules facilitate a satisfying assassin playstyle. That is, for a character to be able to sneak up on a creature and swiftly and silently take them out in a single, well-prepared moment.

Sure, you can simply have a rogue/assassin character deal a decent amount of damage in a single hit (a-la D&D5e sneak attack), but the amount of bonus damage is typically not enough to kill a guard in a single hit, and that seems necessary for balance reasons. Since the damage is not enough to take them out instantly, they can then call for help and your assault feels less like an assassination attempt and more like a decent opener for a combat encounter you were hoping to avoid entirely.

Does anyone have any experience with instakill rules from other TTRPGs? Did they allow assassin-type PCs to really feel like assassins, or did the instakills feel cheesy and unbalanced? Are instakill rules even wise to have in TTRPGs, or are they too prone to being abused?

 

[zarionofarabel]

I have been working on a TTRPG of my own (who hasn't?), and one interesting hurdle I bumped into was how to make the rules facilitate a satisfying assassin playstyle. That is, for a character to be able to sneak up on a creature and swiftly and silently take them out in a single, well-prepared moment.

Sure, you can simply have a rogue/assassin character deal a decent amount of damage in a single hit (a-la D&D5e sneak attack), but the amount of bonus damage is typically not enough to kill a guard in a single hit, and that seems necessary for balance reasons. Since the damage is not enough to take them out instantly, they can then call for help and your assault feels less like an assassination attempt and more like a decent opener for a combat encounter you were hoping to avoid entirely.

Does anyone have any experience with instakill rules from other TTRPGs? Did they allow assassin-type PCs to really feel like assassins, or did the instakills feel cheesy and unbalanced? Are instakill rules even wise to have in TTRPGs, or are they too prone to being abused?

Almost all the TTRPGs I play on a regular basis feature rules that will result in instant death depending on the situation. In most cases it's because the HP vs Weapon Damage means that any weapon hit has a good chance to reduce a target to zero HP resulting in instant death.

Mythras, which has Hit Locations which average 4-8 HP in a Location and a normal Broadsword does 1d8 damage so a single Broadsword strike can reduce a Location to zero HP. If a target gets hit in the Head, usually a 4 HP Location, and the attacker rolls decent damage, the target is killed instantly. Due to how the combat engine in Mythras works, a PC could potentially setup a situation where they can trigger the Target Location special effect to target an opponents Head, as well as the Maximize Damage special effect when using a weapon that causes the required damage, and it would guarantee that the damage done to said location would result in an instant kill.

 

[Whisper-Kitten]

In p1 you have the death strike ability with assassins and slayers. That requires a study of the character for 3 rounds, it be a sneak attack, and the enemy fail a fort save. Players can also coup de grace, but that‘s a whole seperate thing. You could also makee the ability limited by how often a day they can use it and scale it by level.

 

[Morrus]

That's a great use for minions (or whatever your system of choice calls them)--enemies who have just one hit point or who are killed with one hit. You get to easily defeat minions, while the real enemies still have hit points etc. as normal. Assuming your game has hit points, of course. Other systems may do it differently.

 

[Tigris]

I dont really have experience with direct instantkill mechanics.

But there are several methods to make something similar work/giving the assassin experience without feeling bad:

• Have in general many enemies not single enemies this way its perfectly fine/reasonable if a guard has low health so something which can kill them does not necessarily kill everything. Especially when thinking that often new recruirs have guard duty or that part of the "sneaking in" is finding the weak/unexperienced guy to take out.
• One could even use the minion mechanic from D&D 4e / mooks from feng shui for many guards. This way its really more about the sneaking near them. (These sre 1 hit enemies and work well in both games)
• Then you dont have to kill them in 1 attack. Like you can use a garrot like the D&D 4e executioner Assassin had. You could only attack an unaware (you are hidden) target eith it but as long as you grab the enemy they cant speak or run away.
• Then you could have many guards be on elevated positions, which for guards make sense, so if you have 4e style forced movement you can kick them down with an attack meaning that not the attack alone needs to kill them.
• Then another 4e mechanik which the shadow assassin had is the ability to build up hidden shrouds around the target (1 per turn). And then evoke them later for big damage. This means if you have time to observe a guard you can add full stacks to the enemey allowing for a big attack.
• What the other 4e assassin had in addition to the garrot was a single once per encounter huge attack. Which is grest against a single guard (if it has not too much health) but does not feel unfair in a combat since its not just repeatable like sneak attack (thus this assassinate can be stronger)
• The second mechanic the executioner assassin had is an ability to kill enemies off below a certain health. Absolute value not % so this helps killing targets eith not too much health more consistently but does add too much power.
• Ylou could also have poisons (like the executioner assassin) had. They are limited use per day and can add even more damage to a single attack (or other effects and could even be added to food or as traps or on clothes etc. )

I think an assassin needing to figure out how to take out which guard as a mechanic is more fun than just having a general instakill mechanic.


If you want to do an instakill, then you could do it in several stages.

• Like first you need 1 turn to observe the enemy to find the weak points.
• Then 1 action lets you knock them temporarily KO. (This attack gets advantage when hidden or something, to make sure you hit)
• And then 1 action lets you kill a temporary KO target.

This would be a lot harder/less efficient to do in a fight.

Or you could make it even simpler with a garrot or something. A condition which gets every turn worse, similar to the really bsd 4e conditions. When you surprise them thats the surprise round and you even need 1 turn less.


Edit: Forgot to press submit, I see now some answers already mention similar things.

 

[Willie the Duck]

That's a great use for minions (or whatever your system of choice calls them)--enemies who have just one hit point or who are killed with one hit. You get to easily defeat minions, while the real enemies still have hit points etc. as normal. Assuming your game has hit points, of course. Other systems may do it differently.

I generally would recommend something like this -- something as in potentially alternatives like a creature does have hit points, but they are ignored in this instance (sneaking assassin and the target is considered a trivial adversary).

I say this because mechanics that instead allow a sneaking assassin types to do huge amounts of hit points* when they sneak up on someone tend to have the side effect of being really powerful openers** in regular combats. Unless that's the tactical gameplay element you are going for ('let's arrange things so all combats start with Joe's character hidden and with first initiative.' 'there's the enemy assassin, someone glitterdust it before it can hide again!').
*relative to the opposition, see zarionofarabel's Mythras example.
**or ongoing challenges, if they can hide or otherwise get the drop on people again.

 

[doctorbadwolf]

I have been working on a TTRPG of my own (who hasn't?), and one interesting hurdle I bumped into was how to make the rules facilitate a satisfying assassin playstyle. That is, for a character to be able to sneak up on a creature and swiftly and silently take them out in a single, well-prepared moment.

Sure, you can simply have a rogue/assassin character deal a decent amount of damage in a single hit (a-la D&D5e sneak attack), but the amount of bonus damage is typically not enough to kill a guard in a single hit, and that seems necessary for balance reasons. Since the damage is not enough to take them out instantly, they can then call for help and your assault feels less like an assassination attempt and more like a decent opener for a combat encounter you were hoping to avoid entirely.

Does anyone have any experience with instakill rules from other TTRPGs? Did they allow assassin-type PCs to really feel like assassins, or did the instakills feel cheesy and unbalanced? Are instakill rules even wise to have in TTRPGs, or are they too prone to being abused?

My assassin for dnd uses the mechanics of destroy undead but makes it single target and gets it at a lower level with a lower and then scaling CR threshold.

Then they have other damage stuff for enemies too strong to one-shot.

But i also run the game usinf skill challenges, and i consider as assassination to be a skill challenge. No initiative, so combat mechanics, but instead the characters use skills to get to the target and take them out. only if the enemy is too well guarded or personally powerful does it end with a battle.

 

[Koloth]

AD&D has an Assassin class as a sub class of Thief. When the Assassin attempts a kill, it uses a special Assassin's table(DMG p 75). No damage worries at first. Just a % chance of instant kill that varies based on target level and assassin level. If the instant kill fails, you calculate weapon and/or poison damage and proceed. Possible that damage will kill the target even if the Assassination attempt fails.
There is a sub-note that the DM is free to apply modifiers depending on conditions like target awareness, number of witnesses, weather, etc.

 

[RenleyRenfield]

Does dynamite in Deadlands count? I mean... assassin don't always have to be quiet, right? You give a man a lit "red-teddybear" full of boom and well...

That game also had a subtle heart attack hex (spell)... could kill a fella in a heartbeat.

And its regular damage from a good knife and a few raises could easily let a character shush stab a man in the back in an instant-kill.

 

[SpellObjectEnthusiast]

A good way to do it is to have just about EVERY successful application of weapon-to-target be an instant kill/incapacitation. Hit with a sword? You die. Stabbed in the back? Roll a new character. Mauled by a wolf? You guessed it.

Then its not the assassin getting to do something special - its just a world where violence is realistically lethal.

Runequest classic is a good example - most weapons deal about 5 damage and each body part has about 4 hit points. A hit to the head or chest will kill you, and a hit to a limb will disable you. So when an assassin stabs you in the neck while you're asleep and instantly kills you, its not a surprising outcome.