It might look like there’s an arcane ritual going on or that something from a film set has been activated early, but this bed of swirling mist is part of a Dungeons & Dragons tabletop game.
You can see this incredible battle grid on the D4 Dragons & Dragons stream. To see the terrain come to life then jump to session 12 “Devouring Dirt and a Daring Daughter” and skip to about 3 hours 18 minutes.
They’re playing a heavily modified version of Waterdeep: Dragon Heist and have two DMs; Dustin and Devan. It’s the duo-DMs who are responsible for the incredible bit of, and this is a habit they have for many of the game’s central fights.
There are even sound effects for the scene with the bog bubbling and cracking as the PCs struggled in the mud.