How can a character be able to Detect Thoughts on multiple people at once?

Since this video came out (timestamped to the important part), I have been puzzling over any spell I could find to understand what’s going on. While I know a DM can invent all they want for NPCs and enemies, I also know that Monty Martin (the DM of that game) finds pleasure in beating his players with enemies that conform to the same parameters that PCs have (thus making a RAW PC as his villain and outplaying the actual PCs). So I am sure that this demonstration of skill from the sallow-eyed man is an actual RAW spell or ability, though I have not been able to find such a trick since that episode first aired.

Does anyone know of a way that a character can be granted "mass detect thoughts"?