Need help creating an Assassin NPC

[Naez]

Well my player's have pissed off quite a few rather influential people. As such a hired hand is kind of to be expected. However I can't find an official character they wouldn't squash like a mosquito with minimal damage to themselves, nothing short of a 5 man hit squad would even phase them. And I can't seem to customize a character that wouldn't outright kill at least one member of the party before they even knew what was going on.

EDIT: To clarify I want them to live but for it to actually be threatening.

[Karl Aegis]

Be a Wizard. Mindrape somebody. Cast Love's Pain on them. Repeat for how ever many targets you need dead.

[FocusWolf413]

Use a whisper gnome or skulk with the dark creature template and darkstalker. Give it twf, weapon finesse, point blank shot, precise shot, shadow blade, craven, staggering strike, and concealed ambush. One or two levels of swordsage for shadow blade would be great. Get magic items to help boost the hiding ability. Bombard the party with daggers while hidden.
It will have la+2.
Skulk 3 Fighter Feat Variant Rogue 4+ Swordsage 2 is pretty solid. For an increase in level, add more to Rogue (normal sneak attack kind) or swordsage.

Spray them with aboleth mucous. Use dust of sneezing and choking. Drop tree/boat tokens on them. Summon allips in their sleep. Be creative.

If the party has glitterdust, it MIGHT cancel out all of the assassin's hide bonuses. -40 to hide isn't hard to negate when you are getting +23 racial on top of at least a +6 dex modifier.

[Heikold]

If they'll win a straight up fight then don't fight them.

Have the NPC poison/disease their drinks in a bar.

Or, better yet, an old potion seller in the street (fake beard and hunch) could sell them Cure potions laced with whatever you feel like. Because that's when you really want to get poisoned: at a time that you need a health potion. Same goes for potions of Bull's Strength replaced with Wyvern Venom - "I'm gonna need to be extra strong for this!" "You take 3D6 Str damage." "WHAT?"

[FocusWolf413]

If they'll win a straight up fight then don't fight them.

Have the NPC poison/disease their drinks in a bar.

Or, better yet, an old potion seller in the street (fake beard and hunch) could sell them Cure potions laced with whatever you feel like. Because that's when you really want to get poisoned: at a time that you need a health potion. Same goes for potions of Bull's Strength replaced with Wyvern Venom - "I'm gonna need to be extra strong for this!" "You take 3D6 Str damage." "WHAT?"

Even better, make it both str and int/wis damage so they're too stupid to realize what's happening.

[Flickerdart]

An excellent approach to the assassin type encounter is to use a summoner (druids are great for this). You get the numbers parity you want, and the assassin can carry out his hit while observing from afar, meaning that he can try again after learning the party's strengths and weaknesses. Most importantly, it's too easy to spike-kill a PC in their sleep, and that's no fun for anyone; instead, the classic trope "I want them alive!" works wonders here. Use a three step plan:

Step 1: While the PCs are heading to [destination], they are ambushed by a "random encounter" of environment-appropriate creatures. Summoned creatures disappear when killed, so this will clue them into what's happening (a druid can use charmed animals which don't vanish). Good Spot checks will also reveal a suspicious bird (a familiar, animal companion, or Malphas' eagle) observing the battle - unusual because birds usually flee from loud noises. Now the assassin knows how the PCs fight, and with luck has significantly injured somebody.

Step 2: As soon as the PCs take a rest to patch up from this fight, lay down the groundwork for the final fight. The assassin sneaks into their camp and sabotages key pieces of equipment - replacing the wizard's component pouch with a sack full of angry hornets, pouring sovereign glue into the scabbard of the fighter's sword, poisoning the mounts, etc. Meanwhile, the assassin's minions prepare the terrain ahead (setting up trenches, traps, and similar). Once the assassin's job is done, he intentionally lets himself be noticed and escapes towards the trap. The PCs will undoubtedly give chase, especially if the assassin nicked something important like the wizard's spellbook.

Step 3: The real battle. The party blunders into the trap, their equipment sabotaged, the terrain against them, and the enemy multiplying by the minute as the assassin summons new minions to help. He may or may not even enter the fray himself. Illusions are very helpful here - if there are 10 monsters fighting but it looks like 50 more are on their way from a conveniently far away location, the PCs might just give up right away, which is what the assassin wants. It's very likely that success in this fight means not defeating the enemy but merely escaping, and should give the PCs ample motivation to find the assassin again and beat his face in. Since his strategy relies on ambushes and sabotage, he might not even be very good in a fair fight, which means your PCs will feel vindicated without having to wait a few levels before they can curbstomp him in a sufficiently cathartic manner.

[FocusWolf413]

I need to use that in one of my campaigns, Flickerdart. Thank you.

[Metahuman1]

An excellent approach to the assassin type encounter is to use a summoner (druids are great for this). You get the numbers parity you want, and the assassin can carry out his hit while observing from afar, meaning that he can try again after learning the party's strengths and weaknesses. Most importantly, it's too easy to spike-kill a PC in their sleep, and that's no fun for anyone; instead, the classic trope "I want them alive!" works wonders here. Use a three step plan:

Step 1: While the PCs are heading to [destination], they are ambushed by a "random encounter" of environment-appropriate creatures. Summoned creatures disappear when killed, so this will clue them into what's happening (a druid can use charmed animals which don't vanish). Good Spot checks will also reveal a suspicious bird (a familiar, animal companion, or Malphas' eagle) observing the battle - unusual because birds usually flee from loud noises. Now the assassin knows how the PCs fight, and with luck has significantly injured somebody.

Step 2: As soon as the PCs take a rest to patch up from this fight, lay down the groundwork for the final fight. The assassin sneaks into their camp and sabotages key pieces of equipment - replacing the wizard's component pouch with a sack full of angry hornets, pouring sovereign glue into the scabbard of the fighter's sword, poisoning the mounts, etc. Meanwhile, the assassin's minions prepare the terrain ahead (setting up trenches, traps, and similar). Once the assassin's job is done, he intentionally lets himself be noticed and escapes towards the trap. The PCs will undoubtedly give chase, especially if the assassin nicked something important like the wizard's spellbook.

Step 3: The real battle. The party blunders into the trap, their equipment sabotaged, the terrain against them, and the enemy multiplying by the minute as the assassin summons new minions to help. He may or may not even enter the fray himself. Illusions are very helpful here - if there are 10 monsters fighting but it looks like 50 more are on their way from a conveniently far away location, the PCs might just give up right away, which is what the assassin wants. It's very likely that success in this fight means not defeating the enemy but merely escaping, and should give the PCs ample motivation to find the assassin again and beat his face in. Since his strategy relies on ambushes and sabotage, he might not even be very good in a fair fight, which means your PCs will feel vindicated without having to wait a few levels before they can curbstomp him in a sufficiently cathartic manner.

This is so much better then what I was gonna suggest. Use this.