Last time we had a gander at Sword Coast Legends [official site], it was ten minutes of singleplayer questing, monster-slaying, loot-grabbing, and tavern-frequenting. The latest trailer for the Dungeons & Dragons action-RPG follows on from that, but carries the quest over to multiplayer so another player can be Dungeon Master.
It's a curious mode which sees one player deploying monsters, laying traps, setting ambushes, locking doors, and controlling monsters while the heroes romp through it. Come see how it works.
It's not directly a competitive mode, more a weird sort of cooperative with the end goal of having a nice adventure. You don't necessarily want to crush the heroes, but it would be nice to give them a challenge. Perhaps set up a few tricks they'll only have themselves to blame if they fall for them. You could outright murder them, of course, but do people to stop playing with jerkface DMs.
That said, I suspect the DM in this here video is going easy on the heroes as they try not to overwhelm viewers by showing off too much at once. It looks simply but pretty neat all the same. DMs can't directly alter a dungeon's layout, as the computer handles that, but they can change basic level parameters like the visual style, the types of monster it'll contain, number of floors, complexity, and difficulty.
Sword Coasts Legends will also let folks create their own campaigns to play and share, mind, but that's not being shown off publicly yet.
The game's due to launch some time later this year, developed by n-Space with Digital Extremes.