I've run this scenario 3 times now, twice at the high tier and once at the low. In all three cases, the party beat up on Saruna and allied with Badru.
I think that in some ways, the deck is stacked against the poor sphinx, for several reasons.
- Firstly, her attitude at the high tier is worse (unfriendly), while Badru remains indifferent regardless of tier. Furthermore, her Charisma is higher than Badru's, making Diplomacy harder on her.
- Secondly, she's undead, and he's 'only' a construct (yes, an evil construct if there's detect spells flying about, but people seem less 'grr kill' on constructs as opposed to undead).
- Thirdly, every single time I've run it, the party's first line of dialogue with Saruna has been 'Hi, we're here from the Jeweled Sages! Can you help us out?' This makes sense from the party's perspective, it just seems like a bit of a sucker punch to have the first person you can speak to be hostile to the sages. One flubbed Diplomacy check later (that -4 doesn't help!) and you have an unfriendly or hostile sphinx on your hands.
The other point I don't really like about the scenario is the A5 catalog being immediately accessible from the start. If the party goes left first (after the fight, that is), they'll notice the thefts and decide they have to rush downstairs, which can cause them to lose out on masses of Preservation Points available in the other rooms on the top level simply by being too dedicated to protecting the contents of the library.
Sure, the GM knows that they're not in real danger of taking serious losses unless they start taking literal hours to do things, but the players don't, and there's no in-character way to tell them. It seems harsh that they can miss out on the boon just by going left instead of right at the beginning - a totally blind choice.
Other than that, I found it a really fun scenario to GM. The golems didn't get to do much, ever - with their poor Perception and no way to see invisible creatures, all 3 times an invisible party member snuck into the room to do the jewel charging without incident.
For giving them hints on what to do, I had the Crystal Beacon glowing in pulses, which were pulsing in time with the glow of the Sky Vault to show a connection between the two. When the jewel holder got close to the Beacon, I also gave them some empathic prodding from the jewel to indicate they could use it to interact with the artifact.
The final room is also awesome. To paraphrase what I said to my groups;
'So you've traveled through a stargate to reach an artificial island inside a cavern miles below the earth, some bizarre clockwork centaurs are demanding to know your business, and there's a false sun blazing down towards you in a very unfriendly fashion. Welcome to Tier 7-11!'
Both high tier groups fought the marut - one set just hauled off without trying to talk, the second set tried lying to it and got caught. The low tier group did manage to talk down the zelekhuts, and avoid combat (though then they'd used up 10 rounds talking and only barely managed to send the 'abort!' code in time!). None of the groups brought Badru in with them, either.
KestlerGunner - I'm having some trouble parsing parts of your post. You're saying the PCs start 300 ft. above the island, but I don't believe that's accurate. Area C1 says the portal to and from B3 enters and exits there; as far as I can tell, PCs start out in front of the bath house on ground level. The Sky Vault starts 300 ft. up (presumably; the cavern's only 300 ft. high, so it can't start any further away), but the PCs aren't on the Vault.