Tomb of Annihilation’s fifth level, the Gears of Hate, is terrible. Not because it’s impossible (which it is), or because it’s trivial (which it can be), but because it refuses to explain itself.
If you’re unfamiliar with the dungeon, here’s a quick rundown:
See those three pentagonal rooms in the center? They’re on gears that can rotate. This hooks them up to each other or other passages.
Players start in the center and want to make their way to the east, then north to reach the stairway down. The room on the far west has a console that allows the gears to be rotated. It also has an inaccessible secret passage that skips the whole thing, but we’ll get back to that later.
An unsolvable puzzle
You’re probably doing some mental gear churning right now. Allow me:
Out of these configurations, none directly connect the control room to the exit in the northeast. The best we get is configuration 5 which opens the treasure room in the southeast to players willing to cross the lake (there’s an aboleth there).
So what’s a hero supposed to do? The implied answer is “think outside the box,” but the text doesn’t mention how big that box is, how to get out of it, or what it’s even made of. The DM is left to pick up the pieces.
Solutions to the puzzle
There’s a couple of ways players might try to solve this problem. Unfortunately, for many of them, it’s up to the GM to decide how they work and if they’re even possible at all.
1. Leave a man behind
The most obvious and also the most problematic solution. One player stays behind to operate the control panel. Everybody else moves into the middle gear, at which point the operator turns the rooms into configuration 1 to allow access to the northeastern tunnel.
The problem, of course, is that the player who was left behind is now no longer playing D&D. The gears have a bunch of combat encounters so our noble operator is sitting idle for most of the session.
If your players manage to get themselves in this position (see option 2) then my advice is to have an NPC appear once the main group gets stuck in combat. Be it Withers, one of the night hags, Mr. Fox, or the skellington-key-head-man. Have the NPC open the secret door underneath the control panel from the other side and pop out. This can lead to a roleplay encounter that ends in either the NPC operating the controls (Withers has plenty of helpful hands) or the player using the secret passage and meeting up with the rest of the party later.
2. Leave a (magical) contraption behind
Same as the first option, but with slightly more intelligent players at the helm. Using invisible servants, telekinesis, rocks suspended by ropes underneath burning candles, or some other shenanigans, the players rig the control panel to move to configuration 1 on a timer.
Note that if they somehow rig the machinery to go to a configuration like number 4 they will cut off access to everything forever. There’s a few of these “fail-states” present and they can be real headscratchers if you’re not prepared. In that case, my advice is the same as previously: have Withers pop in to be deus-ex-machina.
3. Smash the control panel
For some reason, the control panel is given AC and hp values. If players smash it, we’re in a fail-state again and the game ends. Why was this even added?
If you’re feeling charitable and depending on how you want to rule the next suggestions, the smashed control panel could reveal the hidden passage below. I have a better idea though: destroying the console causes the gears to go haywire! The puzzle now becomes a skill-test like one of those amusement park funhouses, except lethal.
4. Climb the walls
The adventure mentions that “the cogs’ ceilings are disconnected from the walls”. What does that even mean? Do they have their own roofs, separate from the top of the cavern? How much space is there between the ceiling and the wall? Can players fit through?
There are three answers here:
- Yes, there is space to crawl in from the top. Note that if there is obvious space for climbing, the only thing preventing the players from completely circumventing the gears puzzle is the tomb dwarves hanging from the ceiling.
- Yes, there is a gap between the walls and the ceiling, but it’s too small to crawl through. This allows select magical spells such as gaseous form or misty step to gain entry. Worth saying that if your players don’t have these spells this means nothing and if they do it means they can again circumvent the whole thing by spamming gaseous form.
- No, there is no gap. It’s magic. Forces the players to interact with the puzzle on its terms, but reduces their options and might even allow a fail-state to occur.
5. Climb through the doorways
If you think about the physics of the place, especially when considering the maps, it would make sense that there’d be a sizable gap between a walkway and the gear it’s connected to.
That would mean that a player who shifts the gears to configuration 1, for example, could just exit the control room by walking east and jumping down on top of the leftmost gear.
This raises the next question which is why even use the gears at all? If the control panel room can be exited like this, then the northeastern and southeastern tunnel can be entered in the same way. Another question is: when two gears do line up to create a walkway, is there room to crawl through? We end up with a similar set of answers as with the walls:
- Yes, plenty of room
- Yes, but magic (gaseous form, misty step) is required
- No, it’s a perfect fit
Again, the DM needs to make up their mind about this and the implications on the puzzle before running it (to give appropriate hints as players traverse the gears).
The Brixton factor
Instead of just telling us the parameters of the gears puzzle, the designers drop a hint in room 63 (the gas-filled room north of the central gear). What happens next will shock you!
Lord Brixton, proud member of the Company of the Yellow Banner, got stuck in this room when Withers turned the gears and trapped him inside. The text reads: “This chamber is closed off and inaccessible most of the time. The characters can reach this area by reorienting the cogs.”
The implication is clear: when the gears are rotated such that there is no walkway, connecting passages are sealed off. Misty Step could still work since Brixton wasn’t a sorcerer. Note that if a player ever spots this chamber from the outside there should be a visible stream of poisonous gas flowing out of it at a steady rate.
Something else to consider – the magical wardrobes of the Cog of Blood
As a final note on this mess of a puzzle, there is the eastmost gear: the Cog of Blood with its five magical wardrobes. The northern passage is blocked by a portcullis which can only be lifted by opening the wardrobes and defeating their inhabitants.
But again these critical objects can explicitly be destroyed to forever break the puzzle! I don’t really know what the idea here is – imagine a party without access to gaseous form trashing the control panel and the wardrobes. Would they have to sit and wait for a squad of angry tomb dwarves to repair them?
The final solution
I like to stay close to the adventure as written, so here’s how I will run this level:
- The pentagonal rooms have their own ceilings jutting down from the top of the cavern. There is a gap between the top of the walls and the ceiling – just large enough for a Tiny creature to squeeze through.
- The connections between walkways are imperfect, even when they are aligned. This allows a Small or smaller creature to squeeze through and enter the lake from a cog or vice-versa. For instance, in configuration 2, a Small creature can leave the control room or enter the northeastern tunnel from the lake.
- Walking along the outer ridges of a cog requires an easy (DC 10) Acrobatics check. A failure means slipping and falling into the water, which lures the aboleth.
- Climbing into an (elevated) walkway from the outside requires a difficult (DC 20) Athletics check, as the walls are slick and wet. It will anger nearby tomb dwarves.
- The wardrobes are magical and impervious to damage. There’s no good reason to allow the players to ruin their own day.
- Smashing the console causes the gears to start rotating randomly. They move to a new position at initiative count 20 of each round. Each creature in the gears must succeed on an easy (DC 10) Dexterity saving throw to avoid losing their footing and going prone.
- Jumping between two gears as they are rotating requires an easy (DC 10) Acrobatics check, with 8d10 bludgeoning damage on a failed roll.
- If a player is left behind in the control room and is getting bored, Withers appears through the secret tunnel. He was going to trap the players the same way he did Brixton, but failed to notice one of them was still in the control room!
Given the above, the ways for the players to beat this thing are:
- Leave a man behind. Triggers Withers.
- Use magic or shenanigans to time the button press.
- [Not RAW] Wreck the console and use acrobatics.
- [Requires Gaseous Form] Gaseous form spam. Will bypass the whole thing, including the portcullis. Gaseous characters are not immune to aboleth charm though.
- [Requires being Small or using magic] Rejoin the party by climbing through cracks in the gears’ walkways. Best be quick to avoid the aboleth!
So now we are ready to tackle the GEARS OF HATE!