[Pathfinder] [DM help] Designing a Nemesis encounter

[Dellis]

Good day!

I'm running the Council of Thieves adventure path, and I need to design a Nemesis for one of my PCs. As the adventure path is set in a human-prevalent city, she will be an human.

A bit of backstory: she's the sister of the PC, heir of one of the most prominent nobile families in WestCrown. As is normal for Cheliaxan nobles, she was trained as a spellcaster. I'm undecided between wizard and magus, but since she's gonna be toe to toe with my PC, in a duel, I'm leaning toward the latter so she isn't squished by my PC (a level 4 melee-oriented, maneuver-oriented bard). Maybe Diabolist for flavor, if she ends up being high enough that she can take a prestige class.

The thing I need most help with is deciding her level. I already know PC classes count as a CR 1 level lower than their class levels, or equal CR if they have PC wealth (as from the statblocks in the Kingmaker AP).

What throws me off-balance is that my PC is gonna be dueling with her. Only my PC and her nemesis will be involved, and it'll be a fight to the death. That is not to say it'll be an honorable duel - underhanded tactics are fair, as is catching the other by surprise while she's having dinner.

CR is designed around having 4 PC in the same party, duels are... difficult to balance.

Which level should the nemesis be so that it is a "challenging, but not impossibile" fight for my PC, fitting for a climatic questline end - a fight so memorable it'll go into ages, with players recounting their tension on the final ouput with baded breath - that does NOT roflstomp my PC, as kids say these days? She has to feel like her nemesis is more powerful than her... but she can still win, with luck, wits, and skill (as heroes are wont to do).

I want my PC to be able to win using her head - if she doesn't, I'll feel free to make her lose it... Literally.

Hugs and kisses,

A concerned DM

[Ualaa]

You could consider going a mix of Magus with the prestige class Duelist.
Both basically require a one-handed weapon, with an open off-hand.

The Duelist levels will make your nemesis harder to kill, without necessarily advancing their casting drastically which would increase their deadly kill the PC power.

If you're set on building, with the same rules as a PC (similar point-buy, wealth, etc) then a same level and equal optimization would probably be fairly close to flip a coin on who wins.
That's not saying you have to follow the rules that the PCs did.
You could build your NPC to be three or four levels higher, but not necessarily stack things in any particular direction that a PC might do so.
That would allow your 'Nemesis' to absorb a bit more punishment before dying, or to have some potential if the rest of the group decides to intervene.

You could also just have the Nemesis with say thirty mooks, who are ordered to kill anyone that interferes, so the rest of the party cannot assist.
Or maybe it is a public duel, and the masses (or King's court) would not look kindly to someone who cheated.
Maybe the duel is to decide something important, and having assistance from friends basically forfeits the winner is right clause, even if the duel ends... the nemesis could then be a trusted lieutenant of the villain, who was their champion in combat.

The Magus is usually built around Shocking Grasp spells.
And then the trait 'Magical Lineage' to reduce the metamagic cost of one spell by one level, combined with 'Intensify Magic' which allows a spell to scale to +5 levels instead of whatever the base is.
That way Shocking Grasp is 1 die per level (cap 10 dice, instead of 5 dice).
If you go that route, a critical could be absolutely nasty.
But Duelist, with a decent number of Magus levels may feel that martial prowess is fair (and cheat through buffs like Shield or Mage Armor, Shield of Faith potions, Barkskin potions, whatever) but magic pushes things over the top.
With some Magus levels, when things get desperate, the nemesis can 'cheat' and throw their spells into the mix, or if two PCs join the fight despite the rules or potential consequences then the Nemesis can stop holding back and use their spellcombat abilities to full effect.

Or maybe you're looking for a magic focused build, in which case they'd always be using their magic to full potential...?

[Dellis]

I really like your proposals. I might go with splashing magus ans duelist, especially since i'm thinking about making it a dex based magus build.

The part about a no-interference clause is exactly what I needed to keep the party from screwing up the encounter if they interfere.

I'll probably have the Kyton patron of the NPC give them both this challenge: whoever kills the other first in a week gains power. Preferably with suffering involved (Kytons, go figure). Interference by others or involving others voids the challenge. Might make for an interesting quest.

I'm thinking then dervish dance or an agile weapon? And intensified spells and the like. Level 5, since they'll be 5 when the duel is scheduled to take place.