As the book puts it (p. 8!)
During this montage, the Overlord also gets a turn, to describe an event that is directly related to the Overlord or their minions, and tell us what they are up to or how they get in the fellowship’s way.
So, frex, Doyce might say, “When you get to the top of the land bridge to the Midlands, you see something that stops you in your tracks. What is it?” and the person says, “Another sky island has come down. Aaaand, I think there was a town there. Overlord, what’s going on?” and passes it to Doyce.
Or, in a more guided fashion, I suppose Doyce can frame it as along the lines up, “When you get to the Midlands, you find a further sign that Siflae and Ecki stopped here. What does that look like?” for the current person to describe an “event” and then Doyce ties that into what the Overlord has been doing.