pdzoch
Explorer
I like the ideas of making the encoutner not just a fight, but a lateral thinking challenge. That really suits the rest of the dungeon which is a bit more "fairy tale" in feel, and involves several traps/illusions and fights that involve tricks to make them go smoother / be resolved easily.
[MENTION=80982]pdzoch[/MENTION] The idea of a new or rejuvenated chimera being (re)summoned with each misstep is apropos to the dungeon/adventure. And the idea of the heads morphing with each summoning is also apropros to the nature of a chimera. Sort of the same as what [MENTION=29387]Askaval30[/MENTION] was recommending; a recurring monster who keeps coming back with a bit of tongue-in-cheek humor/interaction with the PCs. I think that's smart because it elevates the chimera from being a boring under-level monster ill-suited to an enclosed space.
The idea of the trap polymorphing a PC into the chimera fits with the dungeon/adventure [MENTION=284]Caliban[/MENTION], though in terms of challenge four 11th level PCs vs. one chimera...the PCs are still going to stomp the polymorphed chimera... It's interesting though... Might have to experiment with that!
What would be REALLY sick is to combined all the ideas together: One of the PCs is randomly selected to the be third head of the Chimera! (replace the goat head). Now the party will really be conflicted about attacking the beast!