Had the conversation with Elyssisoriel, which let me drop one clue about the upcoming adventure in the Gorge of Fire, and one clue about adventures beyond that. These clues worked fine--their meaning wasn't immediately recognized, but there wasn't a need to immediately solve the riddle.
There was an attempt by NPCs to ambush the PCs' use of transport via plants by relocating a tree. I tried to sneak that in by suggesting a phrasing of the target tree that would make the ambush work, and that sneakiness may not have been such a good thing for me to do. But after my plan was revealed, I let Lori decide whether her character would have fallen into that trap, and she elected to do so.
So they fought a wicker man near the relocated tree, which just barely managed to accomplish a bit of its plan to capture some fighters and set itself on fire before it was killed. But I think I did manage to imperil Kyle a bit from the flames.
Then they proceeded up the valley, and met a firestorm of smoke and cinders coming down the valley. Resist fire 30 made that pretty much irrelevant in the usual D&D way of turning challenges from fatal to beneath notice. In its wake was a chaos drake (from the Draconomicon); engaging at long range meant that this half-dead from Larissa's cold balls before it managed to make contact, but it managed to take a little revenge on Larissa before perishing.
As I plan for future sessions, I find myself pondering a question of pacing: how long should the trek through the Gorge of Fire be? Here are some of the pluses and minuses of a long trek (labeled with + or - accordingly):
+ It fits the geography. I felt that the Gorge should be pretty long, since on the map of the Land it should be visible as the dragon's mouth. And the flat spot where the "tooth" has been broken off should be near the mouth, because it's already been established that Agondre is missing one of its largest teeth (presumably Kotara-Nar). So the obvious answer is that it might be a thirty-mile trek over difficult terrain to get to the volcano end of the Gorge. (It might be possible to provide some sort of short cut (which is why I'm considering how long the trek should be), but I'd have to add that in; it's not yet obvious that there is such a short cut.)
+ A long trek might have some virtues from a storytelling point of view. There's a nice sort of story buildup about "on the first day it was hard, then on the second day it was harder, and then the third day was the hardest and hottest of all, until things took a twist..." I can't go into too much detail yet, but it fits some of the themes of the adventure pretty well.
+ A long trek with lots of encounters would give the PCs a chance to rack up a lot of XP, which would make them more able to handle the next adventure I have in mind.
- The biggest down side: it might be boring to encounter one fiery encounter after another. I have figured out some ways to introduce some variety, but it could still be tedious.
- A long trek would make this adventure much longer than most of the adventures we've had recently.
- The other big down side is that it's a fairly perilous place, and it's not hard to imagine that once the resist fire spells wear off, things would get more perilous. Especially with firestorms rushing down the valley.
+ On the plus side, I've figured out some ways that the PCs could survive those perils, and even some of the encounters that I thought at first were too dastardly. And my ideas would make for some very nifty moments in a story or a movie.
- However, this becomes sort of a riddle of "how do you overcome this seemingly-impossible challenge?" This sort of riddle works well in fiction. In Three Hearts and Three Lions, for instance, you get the scene with the protagonist fighting the troll, discovering that it's regenerating, and then, in a glorious blaze of desperation and inspiration, throwing the pieces into the fire. Unfortunately, there's lots of more-likely ways for such a riddle to play out in real life:
a) The players might solve the riddle trivially, and tackle the troll with flamethrowers and walk over the problem with ease.
b) The players might never solve the riddle, or do it only after the players get frustrated enough to try some sort of exhaustive search. The scene a few sessions ago where the PCs had a subdued and unconscious ocularon, and were trying one thing after another to find out what would keep it from regenerating, until finally Turok whacked it with a handful of silver coins--well, that wasn't one of the glorious moments of the campaign, either from a story point of view or a player fun point of view.
c) Another possibility is for the players to solve the riddle with hints from the GM. This too risks being unsatisfying, particularly if it results in the GM leading the PCs by the nose.
So, I've learned to be wary of this sort of riddle; just because it would make a good story doesn't mean it would make a good game.
Behold, I waffle. I solicit comments--especially from my players--on how to make that decision.