Level 8 has got to be the highest level Shadowdark material I've read both in this Jam and anywhere which is already a nice thing to see.
Right off the bat I appreciate the secret door that allows the opportunity to go left or right rather than tunneling the crawlers onto a certain path. I'll suggest that the secret room as written is kind of a lock with a key provided in that it will be very difficult, maybe even impossible, to miss or fail as written. A tiny bit of misdirect or uncertainty might help there but it's also not an imperative thing that it's difficult to get into.
The horde mechanic is pretty novel and I'm not sure I've seen another in SD material yet, very well designed from reading it anyway.
The specificity of the thermal-based trap in room two seemed odd to me at first but then I realized that if there's a way for players to anticipate this it gives them a neat way to interact with that sense and of course it's neatly signposted by the lizards!
I digress of course but the early rooms really grabbed me.
The whole conceit for this dungeon is really cool and of course a great use of the title you were provided. I'd be interested to hear about how the hordes work out in playtesting.
My only concern on reading is that the loot might be a little light for the trouble of an 8th level party but that's to taste and balancing for sure.
Thanks for entering this cool idea!