You call taking 20 a glance!?
It doesn't take long to see what happens in this room.
The room explodes in violence. Huge metal scythes pierce the room from every direction, their blood-stained blades seemingly crossing every inch of the space. In an instant, their violence is gone, and the room is still once more.
Across the room, you spot a large wooden door in a niche unmarked by the blades.
A quick look about the room spots several gaps in the storm of metal's coverage, perhaps making it easier to cross the room.
An extensive, minutes-long, search of the foyer-area where Brim stands finds little, until he begins running his hands across every surface. As he does so, a stone slides back, beginning a ticking sound. The tempo of the sounds speed up, and then abruptly stops as the room explodes in violence.
Apparently you've found a timed trigger, giving you a few moments to safely cross the room and into that alcove.