the drow sorcerer-Demonskin Adept got onto the PCs' newly-acquired flying carpet, and headed off to town (a 2 hour trip by flight). His plan was to fly back to town, have a rest - because it was currently the middle of the night - arrange a cart and then come back to collect the books.
As he was flying away from the Bloodtower, though, he noticed signals being sent to him (via lanterns being shaded/revealed) from the foothills around the tower. Now both the player and the PC knew that the wizard whose other-planar tower they had raided, and whose carept he was now flying upon, had been a leader of the hobgoblin armies that roamed through the hills. So he (correctly) inferred that the signals were from hobgoblins who assumed him to be the wizard, flying back to town on his carpet.
The drow did not understand the signals, and in any event had no light source of his own to use to try and send a response, so he just kept going. But the suspicious hobgoblins sent up a flight of wyvern riders to check him out (I statted these as one real wyvern and one real hobgoblin, levelled up to 12th from the revised MM wyvern and from a hobgoblin leader in MV2, and as two 15th lvl minions which were wyverns-with-riders). The wyvern's, with their fly speeds of 8, were clearly closing on the carpet with its fly speed of 6, and the drow decided he would be better off trying to turn around and return to the rest of the party at the Bloodtower, rather than get chased down before he could make it to town. (In mechanical terms, I offered him two options: a 6/3 skill challenge to make it to town before the wyverns caught up, or a 4/3 skil challenge to make it back to the tower.)
The skill challenge was fairly quick and quite a bit of fun. The player tried the standard sort of stuff you would expect: Acrobatics for clever manouevring, Stealth to try and remain hidden from them after his clever manoeuvre, etc. But his rolling was poor (I remember multiple 3s and maybe a 1 as well). While on the Elemental Chaos he had managed to bottle some pure elemental fire, and as a final attempt to get away from the wyvern riders he pulled that out, used his paragon path feature to change his resistance to fire resistance, and then tried to absorb the chaotic energy of the fire to enhance the speed of his carpet. The Arcana check was another failure, however, and the elemental fire escaped (causing damage to him but as best I can recall not to any of his pursuers) and his carpet crashed to the ground (this was the 3rd failure of the challenge, and he had achieved only 1 success).
The other PCs had, in the meantime, noticed the aerial combat - they saw the explosion of flame, and there had also been a Blazing Starfall used by the sorcerer earlier on - and were gathered around the base of the Bloodtower (where the books were stacked on a canvas sheet) watching.
I rolled a % die to see how far short of the tower the carpet crashed - it came up at something around 50 squares. The other PCs delayed until the wizard could act - he double-ran (14 squares, because he has Boots of Striding) and then opened an Arcane Gate at the base of the tower, and 20 squares towards the scene of the carpet crash. (Arcane Gate continues to be on the MVP of wizard utilities.) The PC fighter and ranger went through the gate and joined the sorcerer in fighting the wyverns. Meanwhile, the PC tiefling paladin - before he could run though also - heard a clanking sound coming from the foothills near the tower and saw a phalanx of hobgoblin soldiers quick-marching down the hillside towards him. So he decided to cast Bless Weapon and stay put to defend the tower, the books and the party's rear.
The paladin pushed back the phalanx - which I had statted up as a Huge 13th level swarm - with the Strength of Ten (from his Questing Knight paragon path), but they surged back and surrounded him (using their swarm ability to enter enemy's spaces). And he also found himself under fire from hobgoblin archers hiding in the rocky ground at the base of the hills (8 14th lvl minions).
But even as the hobgoblins pressed their attack, the sorcerer and fighter were dealing with the wyverns and riders pretty handily, and the ranger was able to turn his attention back toward the Bloodtower. He used his Fiery Burst Greatbow to set one corner of the phalanx on fire. The paladin was also caught in the blast, but was able to ignore the fire damage (due to being a tiefling). But he took advantage of the fact that he was on fire to try and set more hobgoblins alight as he attacked with his sword from the middle of the phalanx. (I adjudicated this as him granting combat advantage as he attacked with wild abandon, and being able to make a skill check - maybe Intimidate? - to deal additional fire damage.)
The tide began to turn against the hobgoblins, especially as the sorcerer was able to come back through the Gate to start blasting with more fire (Flame Spiral, I think) and the ranger was continuing to rain arrows upon them. Then the PCs heard a command grunted in Goblin, and then the clank of chains falling to the ground, and saw that hobgoblins still in the hills had released their chimera (15th level, from the MM but with damage updated by me to MM3 standards).
After another round or two the phalanx was defeated and all the PCs had made it back to the base of the tower (there was a bit of confusion for a round as the drow was parked at the tower end of the Arcane Gate surrounded in darkness). I then put down a d6 next to the chimera, set to 3, and announced the start of a countdown. At the same time I indicated that the PCs could see a red speck, glowing like a cinder, in the distance above the hills, but rapidly getting closer. Before travelling to the Elemental Chaos they had already seen evidence that a firedrake had visited the Bloodtower, and so the players worked out what they could see - and the meaning of the countdown - without much trouble.
In the last round of the countdown, I gave the players the option of spending their PCs' standard action to either regain 2 encounter powers, or to spend 2 healing surges. All took up the opportunity to regain encounter powers rather than attack, except (as best I can recall) the paladin, who kept up the fight against the chimera. As a result, the chimera was still alive when Calastryx landed and breathed on the PCs. The players got quite a shock when I showed them the picture of a 3-headed dragon - and from the fact that (as they could see from the relevant page of the MV2) that it was a named dragon made them understandably anxious.
It only took 1 more round for the PCs to drop the chimera, but the fight against Calastryx took several rounds (4, from memory). Her breath didn't play as strongly as it might have, because in the fairly open terrain the PCs were spread out making targetting tricky - and two of the PCs (the chaos sorcerer and the tiefling paladin) had fire resistance. But Rip and Tear (bite attack with reach 3 against up to 3 targets) was a winner!
The players had been hoping that, once they bloodied her, they might kill a head or two, and got a big shock when another head grew - giving her another breath and another Rip and Tear.
Calastryx's dowfall was the PC fighter. He managed to lock her down with OAs and his feat that lets him immobilise a target that he hits with his polearm. The wizard also put a Wall of Fire on top of her (after stripping her fire resistance with his Divine Philosopher encounter power) so that she wouldn't have enough movement to fly off.
She broke out of this trap by using her bite to toss the fighter two squares away (push 3 on a hit, minus 1 square for being a dwarf), and was able to break away into the air and start roasting and chewing on the sorcerer, ranger and wizard. But the wizard was able to have his dragonling familiar breathe a Thunderwave onto her, pushing her back to the ground. And the fighter (14 squares away) was then able to double move and charge, hitting her and locking her down once again.
Things were getting a bit dicey for the PCs as far as healing was concerned - the sorcerer and ranger were both out of surges, and the dwarf started the fight with Calastyrx having only two left. But clever management of their healing resources saw them through - the dwarf second-winded (with his Cloak of the Walking Wounded), opted to use his remaining daily item power for his dwarven armour rather than his symbol of shared healing (he is a Warpriest of Moradin), while using his Healing Word to keep the paladin up. The ranger (who is also a hybrid cleric), meanwhile, used his Healing Word to revive the wizard (who had been chewed into unconsciousness) which was crucial for the subsequent Thunderwave manoeuvre.
So in the end the PCs hung on, and Calastryx was defeated. There was a brief attempt at negotiation - initiated by her, and followed through on (although ineffectually - a very poor Bluff check) by the drow - but the other PCs were determined to keep going. As the player of the fighter put it, "This 3 headed monstrosity is going down!"
