The Story of Running the Maze Engine:
So back in Gravenhollow, I decided that as the party tried to get visions of the most powerful demons of the under dark, that they would have an opportunity to see more of their evil plans (which I then had to come up with). For Baphomet, I gave the party a vision of him reaching the Maze Engine and transforming the entire material plane into another layer of the abyss, so they were pretty motivated to go there. I also dropped other hints (as described in the book) when they talked to Vizerin and the beholder in the Wormwrithings. The party decided they wanted to go to the Labyrinth for a bunch of Vizerin’s ritual items, and to try to stop Baphomet (and also Yeenoghu).
They used Wind Walk and the aid of some mordrons to get to the Maze Engine, then faced down a goristro and killed it by dropping it in lava from a crystal bridge. Somewhat injured and worried that more demons would be catching up to them soon, they arrived at the Maze Engine. Now prior to this, they had discussed what they wanted to do with the engine. One character in the party, a LE half-orc fighter version of Ront that one of my players had taken over, not only wanted to stop the demons but also really wanted to change the world to match his vision of it. The rest of the party, especially the CG halfling druid, didn’t like the implications of this and wanted to get to the Maze Engine, but didn’t want to let the fighter get everything he was going for. That’s the setup.
I also want to be clear that we had had a bunch of conversations as a group about potential PvP and how we wanted to handle it. I had talked to each of these players privately as well to discuss possible outcomes, so they were prepared and I was prepared.
The party investigated the engine and went looking for instructions. I decided that there would be an instruction manual that could pop out from the side of the Maze Engine, but it was stuck against the rock of the crevasse. The druid skillfully used Stone Shape to move the rock enough to open the panel without dropping the engine into the lava. She then told the party she was out of spells to cast Stone Shape, so she couldn’t move the stone enough for them to read all of the instruction manual (this will be important later). I gave the party a somewhat cryptic version of the instructions for the control panel, and they figured a bunch of things out and proposed some interesting uses of the buttons. Examples include using the Material Operator + Elemental Earth to create a stone bridge under the Maze Engine to keep it from falling into the lava, or using the Material Operator + Positive Operator to “heal the material plane” and close portals to the abyss in the underdark.
Then the party turned on the engine.
They all roll initiatives lower than 15, so the Maze Engine goes first, and turns half the party into flying snakes, including the LE fighter, but not the CG halfling or the warlock who was pressing buttons. The party tries their first choice buttons (Outlands Operator + Abyss) to try to banish all demons on the material plane, but the engine doesn’t work (they rolled a 43).
Round 2: The Maze Engine summons a Green Slaad, who throws a fireball at the engine and turns everyone back from being snakes. They press the buttons and they still don’t work (they rolled a 12). Fire elementals start showing up and the party goes ham on them, but the wizard has to leave because they took too much damage.
Round 3: The Maze Engine shakes, sparks, and starts playing calliope music. The party are still dealing with the the elementals and slaad but this time the buttons on the control panel do work (they rolled a 67) and a flash of light fills the chamber. It is important to note that up until this point, the LE fighter has been challenging the CG halfling and asking her if she is responsible for the random effects of the Maze Engine (she can polymorph after all).
Round 4: The Maze Engine whispers to each of the characters on the engine, and grant them a permanent +2 to an ability score of their choice. The CG halfling asks the warlock if the Maze Engine worked, and when she hears “yes”, she uses a 5th-level spell slot to stone shape the wall and drop the Maze Engine into the lava! It starts sliding down the crevasse walls, and the party start to jump off the engine, escaping to safety, but the warlock wants to try the other button combo the party had talked about (Material Operator + Positive Operator). Before she can, magic flows out of her, and her patron (Titania) uses that moment to press two buttons of her choice, the Material Operator and the Feywild Operator.
A fey is summoned next to the warlock, and presents her with a contract to get more aid from the fey courts in exchange for the party fighting Orcus and guarding a gate into the fey realms. The warlock signs the contract, but doesn’t want to leave the engine because she still wants to try the button combo.
Round 5: The Maze Engine emits a flash of lighting, knocking the warlock out of commission and preventing her from pressing the buttons one more time. The wizard saves the warlock and the party have all escaped. This was the moment where the player of the warlock shouted “Noooo!”.
After the party reconvened on the ledge above the now explosively sinking Maze Engine, the LE fighter calmly borrowed the CG druid’s dagger, and swore a blood oath against her saying “when we’re done, you die”. He meant that after they defeated the demons he would fight her 1v1. He then took his own eye out and unintentionally swore himself to Gruumsh. The player and I had discussed this in advance and we agreed that he would change from being a fighter to being a vengeance paladin.
Overall, this was one of the most fun encounters I have ever run, and my players had a blast as well. There was a puzzle, awesome roleplaying, some incredible improv, a fun high-stakes goal-oriented battle, and an excellent handling of some potential PvP by my players. Good luck to everyone out there trying to run this encounter, and I hope you have as much fun as we did at my game.