You walk 80 feet down a corridor, take a right, and after your first step, Mrak becomes motionless and suspended as if in mid-air, and he cannot breathe.
The person immediately behind him realizes what has happened to Mrak: he steps into, and is engulfed by, a gelatinous cube!
OOC:
Combat starts. Players have first action, first-come, first-served, and then the ooze will act.
Mrak, since you are engulfed, an option for you would be to use your action to roll a Strength check to see if you can escape the cube unassisted. I am open to creative solutions, also.