Making a master assassin

[Chaosvii7]

I'm statting out an NPC for a HUGE fight I have next wednesday. I need to construct one last character - a tiefling rogue. Besides the racial abilities, she should be pretty exemplary of a master assassin. Now, anybody who knows me knows I want my monster designs to be unique - I don't mind using creatures from the book or their abilities, far from it. But I want iconic monsters to have special abilities or work in special ways that, while not being against the design philosophy of 5e, makes each fight mechanically different or unique.

I was considering what I might be able to do with her, and my ideas were as follows:



Master Poisoner - She has special poisons only she can use that recharge each round. These'd either be really toned down poisons or they'd be special posions that don't exist in the DMG but have their own special effects.
Parry, and Riposte. Riposte would just be a way for her to get Sneak Attack dice by herself.
Literally just make her Katarina from League of Legends(And I really don't want to do that).



Suffice it to say I'm taking suggestions. She can't have lair or legendary actions, needs to come out at about CR 9, and her chassis can be built around the Monster Manual's assassin, but she needs far more substance to be considered appropriate for what I'm looking for in a creatre. She can have magical abilities, but preferably the only spellcasting she'd have is her racial spellcasting - any magic ability can be considered supernatural, or it can be interpreted that she has a very limited repertoire of spells that give her these supernatural capabilities. The amount to which she can use these limited magical abilities is up for discussion and can be at-will if necessary for the effectiveness of the character.

Any cool mechanical tidbits you can think of to flesh out her design would be much appreciated.

[Malifice]

I'm statting out an NPC for a HUGE fight I have next wednesday. I need to construct one last character - a tiefling rogue. Besides the racial abilities, she should be pretty exemplary of a master assassin. Now, anybody who knows me knows I want my monster designs to be unique - I don't mind using creatures from the book or their abilities, far from it. But I want iconic monsters to have special abilities or work in special ways that, while not being against the design philosophy of 5e, makes each fight mechanically different or unique.

I was considering what I might be able to do with her, and my ideas were as follows:



Master Poisoner - She has special poisons only she can use that recharge each round. These'd either be really toned down poisons or they'd be special posions that don't exist in the DMG but have their own special effects.
Parry, and Riposte. Riposte would just be a way for her to get Sneak Attack dice by herself.
Literally just make her Katarina from League of Legends(And I really don't want to do that).



Suffice it to say I'm taking suggestions. She can't have lair or legendary actions, needs to come out at about CR 9, and her chassis can be built around the Monster Manual's assassin, but she needs far more substance to be considered appropriate for what I'm looking for in a creatre. She can have magical abilities, but preferably the only spellcasting she'd have is her racial spellcasting - any magic ability can be considered supernatural, or it can be interpreted that she has a very limited repertoire of spells that give her these supernatural capabilities. The amount to which she can use these limited magical abilities is up for discussion and can be at-will if necessary for the effectiveness of the character.

Any cool mechanical tidbits you can think of to flesh out her design would be much appreciated.

Whats wrong with the MM Assassin with legendary actions and legendary resistance?

[Giant2005]

Give the Assassin 6 levels of Shadow Monk and a Cloak of Elvenkind - it would be a hell of a fight. The Assassin would strike and then teleport away, hide, reapply poisons, strike again and repeat.

Or you could give the Assassin 2 levels of Warlock so it can see through its own magical darkness (Cast from the Tiefling racial list) and just slog it out more directly. It would have advantage on all attacks for sneak damage and the opponents would have disadvantage on their attacks which would probably result in 1 or less attacks hitting the Assassin and that 1 or less attack would be mitigated further by Uncanny Dodge.

[Chaosvii7]

Whats wrong with the MM Assassin with legendary actions and legendary resistance?

Legendary resistance is fine, but I really don't want to give her legendary actions because the NPC in question is a specially crafted companion character for a player character who is very new to D&D. There's gonna be a huge fight for the finale and everybody in the party has an extra character that they can control in the fight to leverage the potential of getting killed by the relentless onslaught of enemies, combined with the fact that it's a sweet reward for playing through the story of the campaign. Everybody in the party is getting a special NPC(I can show you the rest), and while she is doing fine with her cleric PC, I don't want to overload her with an overly complex NPC that has a million options. I want to give her something that has a few simple abilities that she can choose from each turn to do different things. If she were more experienced as a player I'd let the dogs loose and go to town on it, but she's also pretty fragile as a player and I'd like not to scare her or give her analysis paralysis with the addition of something that takes turns between other peoples' turns, or has a bunch of spells that she has to look up individually and make multiple rolls or checks for.

And again, it's because this is an iconic NPC in the story and I want her to feel like she's controlling something that's more unique than something out of the Monster Manual. She herself isn't very knowledgeable in all manner of affairs of monster design, but I would definitely be doing her a disservice by not making her an NPC all her own like I did for everybody else. Like I said, it shouldn't be painful to read through the statblock and see how her abilities work in tandem with each other, but I think she, like the rest of the party, deserves a specially crafted NPC that has an identity unlike any other listless creature I might throw at her.