Rabbitbait
Grog-nerd
Are the yuan-ti described as being as endless as the DM needs them to be? I think the general idea is to get Ras Nsi and Fenthaza to ultimately help the party, not actually try to kill all the yuan-ti, which would be nigh impossible for a mid level party. Hell, you could make a 10th level party suffer pretty bad if you wanted to, they couldn't deal with 60 snake people at once either.
I just ran it as I felt it would naturally happen. Once the alarm was raised and they realised where the threat was, a large number (but not all) of the yuan-ti and associates started heading towards the threat. The Hydra was also attracted by the sound of the thunderwave.
It could have played out far differently.
- if they had walked in through the front door for negotiations there would have been far more simmering threats and politics
- if they hadn't cast a thunderwave they may have been able to sneak through the complex
- if they had all been captured it might have gone to the slaves scenario
- if b'Urp had been evasive with Ras Nsi he could have been killed on the spot (leading to the others going to the slave scenario).
- if they had told Ras Nsi about Fenthaza's plan then it would have played out differently.
I've really enjoyed this scenario so far. So much of it is so dependent on the actions of the characters, but there are options for when it turns to custard.
However the two characters still trapped in the Fane are at the final part now - if they don't find a clever way to get past the yuan-ti then they will be killed. That will change the game as they have the final puzzle cube. Is it my role as DM to find the answer? Hell no. I hope they figure something out.