So I'm cooking up a fantasy campaign to run for a few friends of mine, and it's got pre-generated characters, who are assassin/spies for a particular nation. Part of the plot, or at least the prologue/setup portion, hinges on being able to kill an NPC with a single strike, and since that's also just sort of their job in general, I wanted to come up with a system that would more accurately reflect the narrative/cinematic system in games and films, of the single strike kill, which isn't as easy in this system.
I also don't want it to be completely broken, but something that is a viable method for combat, given the circumstances, so this is roughly what I had in mind, and I wanted to workshop it. Not sure if I would build this as a Talent progression, or just an aspect of how the game mechanics in general work.
If a PC makes a stealth check to try and approach a target, and succeeds, AND is able to cover all necessary range bands in that same turn, their next action, if it's an attack, will be without any difficulty dice (excluding any special talents the target might have to the contrary), and if the attack lands, it's automatically a crit. This would allow you to insta-kill any minion (since it's a crit), and depending on the amount of damage inflicted, possibly allow a secondary kill as well (the double shiv kill beloved by Assassin's Creed). This allows for the potential to quickly and quietly drop a single, or small groups of targets, while preventing the player from just totally wiping out like a big minion squad. If it's a big squad, it would at least let them thin the herd a bit, before going into regular combat actions. But for single targets, or pairs, it would work quite well.
Since a crit doesn't mean insta-kill for a Rival/Nemesis, I was thinking of the attack having an automatic +result to the critical injury chart when it's rolled, like say +20 to the roll result, allowing the chance (on a good roll) to be able to roll Death even for tougher enemies.
Though as I sit here thinking about it more, I'm wondering if it wouldn't be better to just port over the...I think it's called Perfected Strike from the Star Wars system, with some minor tweaks perhaps. It's a series of talents, that as you buy improved and superior, allow you to just auto-assign different categories of critical injuries on a hit. Start with the minor ones, to the more severe, than the really nasty ones with Superior. And instead have it tied to a successful Stealth roll or something.
I'm not trying to make assassin's OP, but to simply make it reasonably consistent as a way to take out targets, at least weaker ones, with the possibility for improvement in the ability as the character becomes more powerful. And having a mechanic, where I can send my fresh out of character generation, kingdom assassin out to solo a target, and have it actually be viable that they could pull it off.
What do you all think?