How does the Maze Engine in Out of the Abyss work?

Question

Spoilers below if you haven't played Out of the Abyss.

I am running the D&D 5e adventure Out of the Abyss. There is a section in the campaign where the PCs encounter a device called the Maze Engine. On p. 187-188 of the module, it describes what happens upon activating the engine, but I don't understand it. Can somebody please explain?

On p. 187, it says that

after successfully passing the Intelligence Check to activate the Maze Engine, it takes 12 rounds to align itself and activate its magical effect. This suggests that only one magical effect takes place because the Maze Engine is destroyed on round 13.

However, on p. 188, it says that

you should roll a d100 on each of the Maze Engine's turns to determine what it does. This suggests that a magical effect will take place on each of the 12 rounds before the Maze Engine is destroyed on round 13.

The two don't seem compatible to me and I'm not sure what the correct interpretation is. Can someone please help?

Thanks in advance!

Answer 1

The Maze Engine takes 12 rounds to spin up before it is considered activated, and then it is active for 13 rounds before being destroyed

You've misread the text slightly, but I can see why it is confusing. Once a character successfully attempts to activate the Engine, it is actually 12 rounds while the Maze Engine aligns itself before it starts to do anything - it is activating but not yet activated. After 12 rounds have passed, the Engine becomes active and starts producing magical effects - that is when you start to refer to the Shaking Loose and Maze Engine Effects sections. So, once a character has poked the levers, it is actually a total of 25 rounds before the Engine eventually sinks into the magma and is destroyed on the 25th round.

The circumstances of the room are such that a character could conceivably try to activate the engine before concluding the fight with the demon that's guarding it, which is presumably why the time it takes for the engine to spin up and actually start doing anything is specified in terms of rounds rather than just saying, for instance, "a minute" in a more narrative way. The module also makes clear that you should be in initiative mode by the time the engine actually starts to do things, too, since you will at the very least be fighting some mephits.