We just finished off Chapter 4: Zenith Trajectory in a blood-pumping, cinematic finale and it was a huge hit. I thought I'd share how it went here.
I found the layout of Bhal-Hamatugn a little redundant and anti-climactic, so I replaced Zenith and Dhorlot's rooms with other encounters (a kitchen area and a bathing room), and instead made Mangh-Mincto's chamber open up into a huge, open underground cavern.
The room itself had a rushing waterfall in it and some PCs got tackled off the edge by fanatical kuo-toas into a large water pool below. The others navigated down long sets of stairs flanking the pool. They immediately heard a deep, rhythmic beating sound echoing throughout the entire cavern. I used music to capture the moment and it worked perfectly - the first minute or so of this song, looped:
Beyond the Wasteland - Final Fantasy Advent Children
A long stone bridge extended farther in, spanning a gaping chasm. Before proceeding they investigated a cave off to the side and fought Dhorlot, chased him off, and stole his treasure. They rested there and then continued on over the bridge, which soon opened up into a circular amphitheater-type room (think football stadium) with a huge shrine in the center. THOUSANDS of kuo-toas underneath, chanting - the beating sound was their hearts beating in unison. I still had the song playing so the players were freaked out and scared.
They knew Zenith was in the shrine (they were magically tracking him) so they went inside and found him whacked out insane and etc. There was some other mooks in the fight that were all aberration/Far Realm themed (I'm using the Far Realm flavor for the various madness stuff in the campaign). Party knocked Zenith out in a moderately difficult fight, then went back to sneak out.
Sneaking across the bridge was done as a skill challenge (4e has a skill encounter system where you roleplay the use of skill checks to accomplish things; in this case, sneaking across a bridge without disturbing the horde), and they eventually failed, making noise and alerting the kuo-toas. At which point I didn't tell them they had failed or that the kuo-toas had noticed them, I simply switched the song to the 1:45 mark, and everyone at the tables lost their minds.
The horde started swarming up the bridge to get them and throwing javelins, and the PCs started running the hell away. It became a second skill challenge: to escape. Also adding to the panic was the many whips down below - the PCs had already learned of the "more whips = more lightning" notion, and there were dozens of whips channeling electricity amongst themselves down below.
The party did well, escaping all but the quickest kuo-toas, which led them into the next encounter - Dhorlot hiding in a cloud of darkness on the side of the bridge, ambushing them with an acid spray. They hurriedly fought the out-for-revenge dragon, while fending off kuo-toas from behind. They killed Dhorlot, saw the horde closing in, and sprinted off into & through Bhal-Hamatugn.
They made it all the way through the temple, with the sounds of kuo-toas screaming and pursuing them, and ran down the front steps to get to the boat. However, the kuo-toa whips had one last trick up their sleeve, and summoned a horrible, tentacled watery abomination to block their way. The PCs threw everything they had left at it, trying to kill it fast because every round another whip would run out the front door and start tossing lightning bolts into the fray. They managed to kill it, despite two PCs falling unconscious during the fight, hightailed it to the boat and finally escaped.
It was an intense, crazy session that really captured the panic and desperation of the party to escape a murderous horde, while already tired and injured, and get the HELL out of this terrible, terrible place.
The sounds great. I think I will use the idea with the cavern and the bridge in my campaign, too. Really cool!
That's a pretty badass finale! Zenith Trajectory is where the campiagn kicks into gear and starts really get rolling. In my game there is a drow in the party and she fast talked her way into a meeting with Zentih. They came back after with a small battle group and attacked in what I called The Battle of Bhal-Hammatugn.