Running AV right now, been tons of fun. So much fun in fact that I made the possible mistake of indulging my players with too much sidequesting and bonus content when they wanted to follow up on a plotline or interact more with a particular NPC, so they've wound up a bit over-leveled and over-geared for the AP as written.
Which isn't a huge deal, the Elite adjustment exists for a reason, and you can just add an extra monster here and there when necessary. But now they're most of the way though level 9 of the Vaults, and I'm a little worried about the Final Boss.
One nice thing about AV is that the "Belcorra Attacks!" events mean the party can get a taste of what they're up against and plan accordingly. The first of these, on floor 8, went off fantastically - I only let Belcorra stick around for three rounds, but that was enough for the fighter to wind up Confused, he left the thaumaturge bleeding on the ground, and the Wizard crit failed against Feeblemind and had to be carted back to Otari to have his brain fixed. As a lesson that this lady ain't nothing to mess with, it worked a treat.
But they learned it too well, and this last session they had their second bout against Belcorra and it was a whole different story; they were prepared and sent her packing. So now it's HER turn to learn a few new tricks.
Boosting her a level is certainly an option; she's level 12, the party is currently 10 (again, I let them partake of the sweet nectar of sidequests) and they'll probably be 11 by the end, so making her 13 keeps her competitive. But they've also seen a good portion of her spell list for countering purposes, they're all packing Ghost Touch weapons, and they're using strategies like Disruptive Stance. As a GM I'm pleased they're playing smart. As Belcorra I'm annoyed.
But of course she's learning their capabilities from these encounters too. I don't just want to play Rocket Tag and boost her numbers to be scary, the PCs are learning, Belcorra should as well. Can you think of any suggestions to make the final confrontation more competitive that won't just amount to Ghost Steroids?