Last week my PCs completed their second adventure, taking them from level 4 to level 8. I made some huge DMing mistakes on planning this adventure, and I hope writing about them will help me remember NOT to do the same thing again.
A brief summary of the adventure as it happened: Prince Oargev and the Heart of Flame
The PCs found out about two fortuitous opportunities both taking place in the next month. First, House Thuranni was selling maps and notes that led to an ancient temple that contained an artifact of amazing, pure magic called the Heart of Flame. They would sell copies of this information to any and all comers. Later in the month, House Lyrandar was quietly looking for an impressive expedition to hire out their first for-hire airship expedition. They specified that they wanted high-profile passengers on a mission of impressive scope.
The PCs decided to take the train, incognito, to Sharn to purchase the information. While there they discovered that both the Silver Flame and the Order of the Emeral Claw were trying to get their hands on the documents. They'd already missed the Silver Flame, but they actually arrived at the bar where the contact was selling the info while the Emerald Claw representatives were inside, purchasing. They killed the Emerald Claw guards waiting outside the bar, they were drawn into a bar fight, which they used as an excuse to take out the Emerald Claw guards inside the bar. They then let the Emerald claw commander and his bodyguards walk out of the bar, with the info as they went in and bought the info themselves. On their way out, they were attacked by the remaining Emerald Claw operative, and managed to defeat them, though one messenger got away with the expedition information
They then took the train to Stormhome, the Lyrandar base. On the Train, they discovered that they shared both destination and goals with a group of Thrannish adventurers, led Sir Jared Daran and Cardinal Dravot. The Silver FLame party thought they would stand a good chance in hiring the Airship because Sir Daran was the grandson of a much beloved Keeper of the Flame, and Dravot was an up-and-coming Cardinal. Since Oargev was in disguise, the PCs said their best claim was that they had Istav, the Prince's cousin. Istav and Sir Daran came to the agreement not to fight it out on the train, and to be adversaries in the pursuit of the Heart of Flame, but whatever happened, to make sure one of their two nations received the Heart, NOT the Order of the Emerald Claw and Karrnath. The PCs at Stormhome successfully negotiated the rights to the ship and convinced Lyrandar to sneak off without immediately informing the other parties of their departure, giving them a head start. They sent a best wishes bottle of alcohol to Sir Daran, who, I think, they legitimately liked.
They decide to take, not the quickest route, which would have taken them directly over the capitol of the Demon Wastes, but the next quickest, which skirts the Wastes for a while and then heads north to the frozen isles south of the Frostfell, their destination. Along the way they fought off Griffon-riding elves with strange shadow abilities who tried to sabotage the ship, they tracked a huge Fire Manifest Zone that, had they entered, would have empowered their Fire Elemental, allowing it to break free, they discovered a mole on board who was sending updates to the Emerald Claw on the ship's location, and finally, they fought against creatures of elemental ice that disrupted their fire ring and caused the ship to crash on the shores of the Frostfell.
The PCs lost no time marching directly to the temple (along the way fighting more ice creatures and a yeti mammoth hunting party), and then rapidly finding their way to the guardian of the Heart of Flame, obtaining the gem, and getting the heck back to the ship. They stopped for nothing--they didn't even finish exploring the temple. On their way back to the ship they saw, and hid from, the Silver Flame expedition, having just arrived by boat, making their way to the temple. They escaped on their repaired ship and flew over Aundair and Breland to arrive directly in Thrane. Along the way, shadow elves tried to infiltrate their ship once more and Talenta Halfling mercenaries attacked them just out of Metrol. They arrived vistorious, national heroes.