Looking Over Book of Challenges: Pool of Endless Froglings
A four-way intersection is trapped with puzzle-locked doors and an elemental portal.
I like that the self-closing door is gentle enough that someone adjacent to it has a chance to stop it, especially since many later encounters seem to punish that reaction by crushing the character.
Having something to dissuade the players from banging their heads against a puzzle forever is often useful, and an unending swarm of froglings that leave behind toxic gas on death can certainly fill that niche.
While the froglings’ tactics might need some adjustment to make sense in other game systems, the basic idea of having them use a swarming kamikaze teamwork approach is great.
Having treasure hidden on the corpse of a dead adventurer is a nice touch.
The depth of the pool ought to be set before running this encounter.
Similarly, the delay before the entrance door shuts is ambiguous (“a few rounds”). I’d have it happen either one round before the portal activates or set both of them to trigger when another door/pedestal is disturbed.
I’m not a fan of all four doors having the same puzzle solution. Given that the puzzle shows a sequence of four rows of four icons (with the PCs expected to fill in the fifth row to solve it), it’s easy to have a different set of rows for each door while following the same overall pattern. Whether the answer for one door should be shown in the clue for another is up to how hard a given GM wants the puzzle to be.
The pattern diagram makes it look like the rod pattern on the free tiles is a circle rather than an octagon, obfuscating how many different angles a given tile can be inserted at. I’d like that to be clearer, as a subtle clue towards the solution.
One-way portals are lazy, in my opinion. If a player thinks it’s a good idea to jump through a breach that hostile alien beings are pouring out of, I’d rather see what they do from there.
Between having a random number of froglings appear at random intervals and each slain frogling leaving behind a gas cloud for a duration which has a scaling penalty on the saving throw based on how many clouds are stacked in a given space, this encounter expects an inordinate amount of bookkeeping from the GM. I don’t think much is lost by using fixed numbers instead of dice rolls for the number appearing and/or the interval of appearance, and I’d have the gas clouds affect the entire room (assuming the doors are all shut), being a mere irritant at first, then imposing minor penalties after four froglings are slain, imposing moderate penalties after eight are slain, and then finally requiring saving throws against significant effects after twelve are slain (with penalties to the save for each additional four froglings slain). For the non-deathtrap variant (i.e. when the entrance door doesn’t lock itself), the gas can take longer to build up and/or never pass a certain threshold.
I know it’s a recurring complaint for me to mention the boxed text, but how can I just ignore such wonders as “The floor and ceiling have been carved from natural stone, presenting no major obstacles”? And that’s not even getting to the confusing wording of “a green marble pool” (it’s a pool of water made from green marble, not a pool containing green marble) or “[l]arge iron doors, each with a large, sliding iron handle” (I’m not sure what a sliding handle is supposed to be, but I think the intent was a door with a handle and a sliding bolt lock).
Punishing the PCs for interacting with the puzzle during combat is an odd choice, given that solving the puzzle is the only way (aside from magical escape) to end combat once the trap is sprung. I know that’s a consequence of 3E’s general combat rules, but I’d let them interact with it without provoking attacks of opportunity (or equivalents in other systems).
In my eyes, rolling for puzzle hints is terrible design. It fits the preferred playstyle for some players, but I’m not one of them, and I’d rather not use a puzzle at all than do that.
Even worse is having a dice roll for trying a brute force solution with the minimum possible completion time being 3 hours when there are literally infinite enemies pouring into the room through a portal that cannot be disabled for more than 1 minute at a time.
These sorts of puzzles are always tricky to evaluate because so much of how it feels depends on the greater context it’s used in, both in the game and as it relates to a given group’s metagame expectations. That said, in the right setting, this is an excellent puzzle. The constant flood of minor enemies presents a sense of pressure without being overwhelming (at least initially), and having some of the tiles rotate by more than 90° per row can make it harder to spot what is actually a fairly simple pattern. However, it’s important to keep in mind that this is likely a deathtrap if the players can’t figure out the puzzle (unless the froglings are willing to take captives and the gas is nonlethal), so I’d save this for a climactic moment rather than using it at a random location.
On which note, this should probably go without saying, but there’s nothing wrong with eliminating some of the doors if a four-way intersection is unnecessary.
All in all, if a deathtrap puzzle would be a good addition to a given game, this is a solid one to use (modifying the aquatic-theme to whatever would be more fitting is trivial, as an added bonus). Alternatively, avoid the “deathtrap” aspect by not locking the entrance door, and it becomes a fine puzzle template for a wider variety of situations.