Glaivelock gestalt optimization Helo

[Nosta]

I want to build a melee monster and I I came up with the though of a gestalt glavielock.
I understand it somewhat but what i'm trying to figure out is what is the best class to pair it with
and from there how to optimize it. I was thinking factotum for extra actions but then I was thinking of rogue to add on more damage from sneak attack. so dose any one have any ideas on how to make this Npc of mine in to a strong boss for my players. players levels are 12 and there are 3 of them

I want this to be a tough but winnable fight for my players

[xyianth]

zhentarim soldier sneak attack fighter 9/scarlet corsair 5. Take the Imperious Command feat. Gives you +6d6 sneak attack and the ability to intimidate everyone within 30' as a swift action that cowers. Plus you are a scary pirate.

[Troacctid]

Since this is an NPC, and specifically a boss fight, traditional optimization techniques don't really apply. What you should be focusing on is making the character and the fight scene exciting and memorable.

First off, the glaivelock needs a hook: some unique aspect about them that makes them stand out in the players' memories. Maybe they speak in an over-the-top accent. Maybe they're a numbers geek and claim that they've run the numbers and have a 97.2% chance of victory. Maybe they have a really cool hat. Maybe they have a duck nesting on their head that they don't notice no matter how often people try to point it out. Maybe they're a mime who fights by swinging an invisible sword. You get the idea. Be creative.

Secondly, they need a proper arena to fight in. A glaivelock works best in close quarters because of the full-round action required to use the invocation. An obvious answer is to put the encounter in a cramped space where the PCs have little room to maneuver. Or perhaps it's a larger area, but there are teleport traps that drag the PCs back into melee range if they attempt to kite. Or perhaps the glaivelock stands in a small safe zone in a room filled with hazards (perhaps there are some Chilling Tentacles already laid down), so players have to engage with him in order to avoid the hazards.

Thirdly, you want to make sure the numbers add up right. Consider your party's average damage output per round, weighted to account for AC and saves. How many rounds do you want the fight to last? Make sure your bad guy has enough HP to survive. Damage reduction, energy resistance, spell resistance, and concealment can also be useful.

Lastly, I often like to spice up my bad guys with a neat race or template (which can even double as a hook). With NPCs, you have a lot more freedom to use relatively obscure templates like Voidmind (there's a tentacle poking out of a hole in the top of his head!), Lost (he's been driven so mad with hatred that he can literally spew bile at you!), Pseudonatural (he looks human, but he's actually an eldritch monstrosity whose true form would drive you mad!), Entomanothrope (he's a were-wasp!), etc.