Okay, I have a group of six characters going through this adventure path. I haven't really modified it much to make it more difficult, which has had the effect of slowing down the group's level advancement. However, since they've largely had a surprisingly easy time with many of their encounters (not all, some have been very close calls), they're getting too big for their britches. The fighter, in particular, is especially bad. He has a pretty high AC at 26 and has a pretty amazing damage dealing ability.
So, there is a possibility that they may try to throw their weight around when they approach the Arkona's. Obviously, given who the Arkonas are, this won't go over well. So, suggestions on how to maximiaze their butt-kicking ability, and hopefuly properly humble my party. PCs biting the big one isn't an issue, I just want to be fair about it. :-)
1. Glorio Arkona is a rogue, but a rogue without the means to sneak attack is a very sad rogue indeed. A similar problem plagued the Skinsaw Man. My suggestions for fixing this include
a. Giving him buddies to flank with. A few more rakshasa in the room should do the trick.
b. Ways to make the party flat-footed. Grease (how many ranks in Balance do your PCs have?) and glitterdust are good core ways to get multiple PCs at once.
2. Do you allow non-core material? If you do, Practiced Spellcaster is a must-have feat for Bahor (and Viamanda, to a somewhat lesser extent). For Bahor especially, because Practiced Spellcaster gets him another scorching ray. If all three hit on a sneak attack, that's 27d6 of damage right there, no save. Telling Blow, which adds sneak attack dice to his critical hits, would also be a choice investment.
3. Equip the mook rakshasas! They're supposed to have standard treasure for a CR 8, after all. I recommend some disposable items that'll bring some pain to your party. Mine come preloaded with offensive scrolls and beads of force, to isolate any pesky PCs capable of actually hurting them.
Some good ideas. I know what I'll be doing tonight while doing laundry.
They do have the dagger and they haven't figured out what's up with it, despite having had some hints along the way. Like the dagger failing to injure an imp and a vampire spawn. And I would imagine Bahor and Vimanda would probably be willing to bury to hatchet, so to speak, if an attack seemed imminent.
Man, those two giant cobras almost wasted half my party tonight. I can see what Paizo means by the Arkonas having a glass jaw, though.