Lord Blot is a sentient sphere of annihilation.
It maintains a low profile in a remote area of a larger kingdom, where it enjoys both limited anonymity and territorial independence. Local rulers know it exists, sometimes referring to it as the Lord in the Pit or the Floating Tyrant, but they also know that they have no way to destroy it. Since Blot seems to have no territorial ambitions beyond protecting its lair and a small region around it, local authorities simply ensure that all roads and traffic avoid Lord Blot’s tiny realm. They also do their best to keep its existence quiet. Records say little about the area, and any reports from the area tend to be destroyed. Maps of the larger kingdom or realm show just forested hills here, with no indications that anything interesting is to be found there.
Those few sages, scholars, government officials, and others who know that Blot exists generally avoid meeting it, as any such encounter is deeply unsettling — and often dangerous.
That said, Lord Blot is eons-old. It knows things about the wars at the dawn of the cosmos. It knows lore about demons, devils, angels, and more. It knows about old spells, ancient magical items, and more. And it quietly collects information on the status of these old, magical things and beings, making it a great resource for particular kinds of information.
And so, from time to time, people in-the-know realize that they need information from Lord Blot.
At which point, they often start looking for someone else to make the trip, unwilling to meet Blot in person themselves.
It’s easy enough to understand their reluctance, to understand why they might be more inclined to send some adventurers like the PCs than to go themselves. For Lord Blot demands knowledge in exchange for any service or favor it provides (including letting visitors leave its abode alive).
Knowledge doesn’t sound like much of a sacrifice.
But Lord Blot only trusts knowledge that it digests.
A book, or a scroll, or a living intelligent being must be consumed by the sphere before it will yield anything it knows.