So, I've seen (and really liked) the Occultist rebuild of Barzillai Thrune, but since I haven't allowed Occult Adventurers material and I'm not too familiar with it myself, it seems like too much of a curveball.
I do want to clarify that I really appreciate all the thought and effort that the Paizo team has put into creating this AP (which has been a lot of fun for my home group), but Barzillai himself just doesn't seem that interesting of an encounter (almost anticlimactic, which isn't necessarily a bad thing). He's okay at almost everything, but not strong at any one particular thing and if the party gangs up on him I don't see Barzillai lasting very long at all.
Now, I've already spoken with my group about making changes to the AP and they've agreed. I'm running books 3 and 4 as more of a sandbox than written, allowing the PC's to drive the action and focus on the things they find interesting. They also know that I'm rebuilding Barzillai.
On mulling over Barzillai's background, motivations, character, and actions throughout the campaign, he doesn't strike me as either a high WIS or high INT guy. His plans are dramatic but needlessly complicated and at times vindictively petty. He doesn't seem to have a head for strategy, and severely lacks common sense. What he does have as an abundance of ego and magnetism- which says CHA to me.
I'm strongly considering rebuilding Barzillai Thrune as a Tyrant Antipaladin, with a focus on intimidation and fear effects. The Antipaladin's aura of cowardice is handy in this regard. I'm also going to be adding the Invincible simple mythic template to him, partially to make him significantly harder to kill, and partially to reflect his metamorphosis to a Genius Loci. The combination of the template and new class make Barzillai a lot sturdier, which is important because my PC's will be absolutely devastating at 13th level judging by where they are now.
So, my questions are three:
Are there any lore considerations/contradictions where Barzillai being an antipaladin would be problematic? I'm thinking at the least at the time he spent masquerading as a traveling scholar and infiltrated the Sacred Order of Archivists. I'm also not sure if an antipaladin can function out of their own ego or if they need a divine patron.
Are there mechanical concerns? Much of his tactics would have to be rewritten, seeing that this is a full rebuild. Barzillai would be far more focused on combat than spellcasting, which I think is fine. Not every BBEG needs to be a spellcaster. It helps that 75% of my PC's are good aligned.
Finally, do you think it would be a fun and challenging encounter, particularly since we are planning to end the AP after the 4th book?
Interesting. You know, Thrune as an Inquisitor is basically a melee character, with his written tactics designed more for the big Temple battle than the room he's found in. (In that room, he's in melee round one.)
I subbed in Forceful Strike as a 4th level spell, and Resounding Blow as a 5th level one. That leads to this given Weapon of Awe up as well:
• Hasted Power Attack Greater Bane Weapon of Awe Resounding Blow While Judging +3 flaming impact heavy mace: +25/+25 (see below)/+20/+15 (2d6+21+1d6 fire+1d6 sonic+4d6+Fort 22 or staggered 1 round (different if crit)/19–20 if crit: shaken no save, Fort 22 or staggered 1 round, stunned 1 round, deafened 1 round) free action 15 round/day,
• Second attack with Forceful Strike +25 (2d6+21+1d6 fire+1d6 sonic+4d6+Fort 22 or staggered 1 round (different if crit)+10d4 force and bull rush CMB +15: Fort 21 half force damage and no bull rush/19–20 if crit: shaken no save, Fort 22 or staggered 1 round, stunned 1 round, deafened 1 round)
That's 49 points on average per hit, plus 1 or 2 Fort saves. Those Fort saves cause significant problems for rogues and arcanists as it stalls them in melee range.
You can probably do better with the anti-paladin and smite good, of course, but it's a lot more effective than his ranged spells tactic, which you're right are completely underwhelming.