It is no secret I love second edition Ravenloft. Back in the 90s, my favorite supplements were the Van Richten Guidebooks. Not only did they offer great material on customizing and running monsters, but the examples and strategies peppered throughout the text offered ideas for adventure. The monster hunt/investigation formed the backbone of the series. In each release, Van Richten related tales of is encounters with creatures like the Gibbering Golem, usually providing some background and a flavorful description of the menance before proceeding into the details of his investigation process. For me, the investigation was the most interesting aspect of the guidebooks, and served as a useful template for adventues. Over the years I ran many such scenarios and they were always my most successful sessions. Here I wll offer some advice on creating an effective monster hunt.
The best monster hunts in my opinion are free form combinations of location based adventures, event-based and character driven adventures. The driving force on the GM's side is the monster and the community or people it threatens. The players should always be free to engage the hunt or not (though they can't be assured immunity from the creature if they leave the area after attracting its attention).
The player characters themselves will determine much of the flow of the adventure. They are the monster hunters afterall and the hunt is for them to plan. However the threat needs tonhave its own agenda and schedule. Suppose the adventure is set in the secluded mountain village of Grega, where locals have been dissapearing in the night. Eye witnesses report seeing a strange beast near the scene, though accounts of its appearance differ somewhat. As the characters investigate, you will want to have an idea of the monster's attack schedule and its overall aim.
The first real work is to develop your monster. Before you create any stats, think about what kind of threat you want the party to face and try to devise an interesting backstory. In the above scenario, you might decide that the twist is there is more than one creature. That these are unusual golems fashioned from different animal parts by the local priest as part of a failed effort to protect his people. Perhaps the priest continues to make more golems in an effort to eradicate his original creatures. He isn't evil, but he does have an interest in covering up the truth which could come into play during the PC's investigation. Alternatively, the priest could be evil or have a warped sense of right and wrong. Maybe he created the beasts to give the populace something to fear so they turn to his god for aid. It is all up to you.
If the threat is intelligent, give it a personality and motivations. Is it killing for food? out of rage? to bring justice? There is nothing wrong with a simple answer, a vamire hungry for blood is just as entertaining as a criminal mastermind. The trick is to mix things up; never rely on one type of threat or one kind fo motive.
Next you should establish some powers and stats. I am a big fan of unique monsters (even if they are standard entries from the monster compendium). Making the monster unique increases the importance of investigating the threat before going in guns blazing. Not only will the players need to assess its strength, they should discover its weaknesses.
To continue the golem example, maybe the creatures are largely invulnverable to normal attacks (not totally invincible to mundane weapons, just difficult to kill with them). The PCs might even try to take them on at first, only to watch in horror as their swords and even their spells fail to yield the desired effects. Figuring out their weaknesses is going to be key. An easy way to determine the weakness is base it on the monsters' creation. So in this case, the golems may have been molded by a knife blessed in local waters, and if the players bless their weapons in the same fashion they can harm them. Whatever the weakness it should be discoverable through investigative means. So the blessed weapon weakness could be learned by tracking things down to the priest or finding a local grimoire describing the ritual he used to create the golems.
Map out the area where the adventure takes place. If this is to be a hunt, the players need places to explore. If there is a village or town, map that out as well. Be sure to include ample sites for investigation (libraries, dissapearance scenes, dens where the creature sleeps, trails, etc). Don't be affraid to throw in incidental locations for fun and exploration. Old mine shafts, isolated cabins, and even the occassional manor house. These may or may not be connected to the threat. But either way, they are potential sites of confrontation with your monster and even sources of information on the threat. If the creature has a lair, be sure to elaborate on that with a map.
Presumably the monster threatens people. They could be a community, a small family, or even the adventurers themselves. Whoever they are, you want to flesh them out a bit, particularly people of interest (those conncected to the threat as victims, backers, eye witnesses). Before play starts you want to have a sense of what makes these folk tick, and you want to create interesting standouts for the PCs to interact with.
These are great adventures to drop on player characters passing through, but if the players aren't on site, they could be summoned by victims who have heard of their exploits. Personally, with monster hunts, I don't like to be too heavy handed or work on overly contrived hooks. At most they may witness an attack or be near after one occurs and get drawn in that way, but leave it in their court. They either express interest in the adventure or they move on. Monster hunts are pretty simple to design, so if the players pass it up, it isn't a big deal,
Hopefully I can address this subject in more detail later. For now, I hope this has been helpful.