All of the most memorable encounters my group has played through have either been premade encounters spiced, salted and flavoured and delicately cooked in my creativity or ones that directly grew the garden of my imagination.
I also like to hack and slash from pre-made modules and re-thread them into the adventure somehow or other.
One of the coolest for sheer soul crushing terror factor was one I stole from the House on Gryphon Hill which is a Ravenloft module. The party had just dragged their way through the Swamp under 'the Creatures' control to get to the town. Their contacts with the nasty elements (leeches, swarms of mosquitoes, cutting plants, bloody mist and spitting frogs) resulted in the party contracting the Delerium Sickness described in the module. On their last legs and suffering from fever and strange visions they drag themselves to the steps of the town's Sanitarium. They awake from their delerium in a room with some freshly dug graves from which the Creature and her harpies burst to hover above them in the air. The Creature was massively above their level as were her Vampire helpers (I used creatures from Open Grave, I think, and scaled them just enough so that it seemed like victory may have been an option, but it wasn't really at all. The module suggests that this is a fast, violent and brutal massacre. So with three massively powerful vampires dominating 3 of the 6 man party that is exactly what it was. But everyone got into roleplaying the Domination, and making attack and damage rolls against each other. Total slaughter. And noone was really sure if what was happening was real or not. high emotions. Loadds of fun.
I had placed several important features around the room, things tucked away in the shadowey alcoves that would reveal the Creatures motivations and weaknesses, and a curtain that covered a doorway that would have sent sunlight streaming in and causing the Creature to become vulnerable. but they didn't even move out of it's Cloud of Something Really Bad. So all that potentially useful future information was left undiscovered.
Of course they woke up later after the hallucinations and fever had ceased. It had all been a dream, and in their delerium that had wreaked havoc through the town, damaging shops, public property and their own gear. And though awake they would periodically suffer from the Delerium on later occaisions depending on how close they were getting to the heart of the matter.
A pretty cool way to establish a relationship with the Villain. I'm not sure if that is exactly as detailed in the module. I have refitted it all to fit into my story. The town is actually Loudwater, but fully expanded into a full blown city. But I don't call my campaign Forgotten Realms, i call it the Broken Realms, and things are about to turn horror on my PCs (well, it's already started. If your interested this is a brief outline of the 'plot'. otherwise, skip the next paragraph to get back on topic. I would 'hide it' if i knew how (what tag do I have to wrap the text in to hide it like a spolier?)
Strahd is the 'Alchemist' from the Ravenloft module, but he has a shard of the dead goddess Mystra lodged in his head, from when the apparatus that created the Creature, exploded under the stress of seperating the Mad God Cyric from his shell and freeing him from his divine prison right from under his captors noses and leaving behind only his Shadow and without raising any suspiscion. The apparatus had already been damaged slightly when Strahd tested it on his lover, seperating her from the essence of her family curse (female heirs posession by a powerful demon) creating the Creature. The demon Creature almost escaped, hellbent on killing Strahd, as she attempted to break free, forcing him to use a large piece of his Mystra Shard to displace her in time and space. Encouraged that his Apparatus worked, he set to the task of freeing his master. Unaware that in the struggle his incredibly fragile and precise invention had suffered an almost imperceptible but fatal fracture. He freed Cyric but lost control of the machine, causing some of Cyric's energy to escape and lash the nearby regions. This foul, depraved energy will eventually come to be known as the Greyplague as it becomes to spread and deform Toril. My Pcs were all struck with it receiving 'Grey Spellscars'. Cyric spiralled misdirected into the Shadowfell, but free again to inflict the world with his insanity he begins to exert his influence on the world subtly, attempting to gather the shattered pieces of Mystras dead body, which he designs to join with his own mutilated body (my Cyric is a twisted version of Vecna). The Mystra Shard lodged in Strahd's head has caused him to forget his identity and influenced him to protect Loudwater from the creature who he knew would find a way to return (which is what is just happening as the PCs arrive in town and enter into the story an Aboleth and Goodman games Curse of the Kingspire). She sends her minions, goblins who have taken up the banner of the Red Hand, gathered in the Bog to raid loudwater and dismantle the protective circle Strahd has placed, stealing the key artifacts from Loudwater's founding tribes that he has used, and kidnapping one descendant of each of those tribes to use their blood to break the Seal, including Strahd himself... (yeah, that's right... raid on Loudwater combined with the first in Scales of War) as he has to fix the broken Apparatus! And pay for the suffering he has caused the Creature of course. Then of course she can use the Aparatus to finally destroy her other half and free herself forever from her prison of flesh, fully incarnating on the material plane. When the PCs finally rescue Strahd, who they call the Alchemist, they will discover he has something lodged in his head, and hopefully help him remove it (it causes him terrible pain). Which means he will revert to who he truly is: the genius servant of the divine incarnation of all that is depraved and insane, Cyric. While helping the PCs so as not to arouse their suspicions about his true nature, he will use them for his own designs and use the apparatus to achieve immortality, reaching his full incarnation as Ultra Villain Vampire Strahd Von Zarovich!
Another one I can remember, I used 'Escape from Sembia', one of the first adventures available for free. Actually, the PCs are looking for 'the Alchemist, Strahd' to deliver that confounded scroll to him. Anyway, after some serious grind with the Hobgoblins outside the town i redesigned the next encounter with the skeletons. I plonked a defiled cemetary down just before where the skeletons were. There was a lifeless tree inside the cemetary, scrawled with bloody evil runes and hexes that radiated pure evil. Shrunken heads hung from the branches. But to carry on on that path they had to cut through it as there was sheer cliffs to the right and a sheer drop to the left. As they crossed the Cursed Tree made Fear attacks agains their Will each round as the heads began to scream at them in an unintelligible language. I can't remember what was happening or how I set it up mechanically on a hit (or was it a failed Sthrow? or a hit triggered a SThrow which if failed ... can't recall right now) Anyway, they furiously wrote down the nonsense, but it made no sense and they relaxed when they got through to the other side of the cemetary, shaken but unharmed.
Only to discover rising from the ground ahead of them, a group of headless skeletons that pointed at them silently before attacking them brutally and mindlessly. I think they might have just destroyed the skeletons as the heads called out to them 'Rorre! Rorre!' if I hadn't rolled a natural 1 for the skeleton wizard's attack and ruled that the magic bolt had strayed and smashed into his allies back. The hit skeleton turned around furious and one of the heads on the tree began shouting 'Norbac,Norbac!' Yep, a classic, the old: 'they are talking backwards trick' but they were all new to RPG, so an old trick is a new trick. Rorre, being Error, as in you're making a mistaking attacking those skeletons. And Norbac is cabron ... yeah, we play in spanish, so you'll have to look that one up! Suddenly one of them twigged and they began furiously translating what the heads had screamed at them earlier. Only I had them under time pressure, forcing turns.
The heads were basically begging them to break the curse and return them to their bodies. So caught in the heart of battle they found themselves suddenly trying to get back to the cemetary and avoiding destroying the skeletons that continued to mindlessly attack them. Of course, running back into the cemetary meant facing the pure evil and hatred of the Cursed Tree, unwilling to release it's victims so easily! but when they realised the skeleton bodies were unable to cross into the cemetary (otherwise they could have got their own heads back) they were able to concentrate on getting the heads down from their as a team.
So what could have been another hack fest turned into a very fun, memorable and exciting encounter that was resolved with wits of steel and not twits with steel. I could probably look up the mechanics/features I added. I could describe some other ones I have altered or even made up, but i'm not sure that's what you wanted TarionzCousin, as opposed to encounters as is, pre-made.
