As noted above, this event will likely draw several waves of treasure hunters, bandits, con artists and affiliated parasites, enough to structure much of the early campaign around. Any authorities nearby (town reeves, provincial governors, imperial witch-guard, etc.) will be sending their own teams to investigate, which will be arriving in stages according to their distance and degree of concern. Imperial arcanists and independent scholars may mount their own expeditions to study this phenomenon, as well as druid-circles, fey courts, and perhaps even a league of the wise and powerful, à la the White Council. This in addition to the oracles, seers, hedge-prophets and other quasi-spiritual stragglers who will be filtering in.

Everyone will be interested in this event, either to harness its power, understand its cosmic import, or just to get a leg up on the competition. Town officials, especially those who have just gained a level and are feeling uncommon mighty, will likely be the first to arrive, followed fairly soon by druid-scouts using tree stride and wild shape, and representatives of other parties who may have teleported a long way, but are still dropping out a safe distance from the site itself.

As for Lord Angmar, you know him best, but I would suspect he’d send a top lieutenant with a detachment of fast riders, perhaps with a few homing doves for updates along the way. I would also expect him to be requesting divinations from every member of clergy capable of posing divine requests, in hopes of learning as much as he can as early as possible. The celestial switchboards will likely be overloaded with divination requests from all across the continent, if not around the world.

And don’t neglect the monsters, some of whom may have the sudden drive to discover the source of their newfound power and attempt to drain even more of it. That won’t be possible, but they won’t necessarily know that, and I’d think quite a few of them would be converging on this location—a parallel set of arrivals overlapping with the humanoid authorities, researchers and other mixed nuts. I’d even expect one or more teams of other low-level adventurers, PCs in all but name, who have taken it upon themselves to save the world from whatever’s just happened—and with that fresh new level, they’re feeling more capable and righteous than ever….