As a DM, I struggle with how much information to give at the table. My natural inclination is to just spill everything at once. Lately, I've placed safeguards against giving away too much. For example, I used rumor tables a few weeks ago. Last week, I did a few things to make sure the PCs didn't walk away the entire plot along with monster names, descriptions, stat blocks, and turn ons. To accomplish this, I used a weakened sage and a library with missing tomes. Instead of leaving with all the answers, the PCs left with a series of clues for where to find them.
The timing of Mike Mearls' article on sages in D&D made me laugh since last week the PCs met another great sage of Arcadia. Lilith, an eladrin who built a tower as a haven for those in need, lives even though she is well over 1500 years old. Born during the Age of Song, she has firsthand knowledge from the Age of Legends and the events that are of particular concern to the PCs. However, she is weakened from her advanced age and the main subject, the Shadow, causes her to faint if she gives it more than a passing thought. She is not useless to the party but perhaps a bit less useful than they desire. This weakness gives me a great in-story reason why she can't just tell them everything they would like to know and leaves them a little less frustrated.
In addition to the sage, the tower has a library with volumes going back to the Age of Song and the town has other residents who might be useful in some way. To frame their search through these resources, I ran it initially as a skill challenge and then allowed it to progress to skill checks for additional information. Some of the party went to consult the tomes. Others huddled around one of the Shadow Army collars, determining how they could be removed. I tried to make the players be as specific as they could, although the initial round was pretty generic. Each round built upon the last until they had a basic idea of what happened. They determined where in the library the books they wanted should be. Then they started looking through the books and found that the ones they needed the most to learn about the Shadow were gone. This led to questions to the staff and townspeople about where the books might be and, if they were taken, who might have taken them.
For those studying the collar, the progression wasn't quite as natural. The rogue studied the latching mechanism which looked much more complicated than it is. Likewise, the patterns of the arcane energy surrounding the collar seemed intricate at first, but ebbed and flowed in the rhythm of a popular children's song. This knowledge gives them a leg up if they try to remove the collars during combat. They also found that creatures without their collars will still be a threat, but they instantly lose the bonuses being a member of the shadow army gave them. In game mechanics terms, they lose the shadow origin and the bonuses to stealth and intimidate.
Overall, the result was great. The players seemed to enjoy the skill challenge. The PCs received valuable information, most importantly clues that they can investigate further. I didn't give away everything I have. This will mean less prep time for me in the future and gives the players some real decisions to make. Do they try to find the missing volumes when they get to Andernach or do they continue on in their quest, worried that each passing day means an increased likelihood that the kidnapped noble will die? Slowly getting the clues about what exactly the Shadow is sets the tone for the final encounter of this campaign arc and also gives me an opportunity to find out from them what their worst fears about it are. The guesses and jokes that result are excellent fodder as I nail down the final details of the upcoming encounters.