by Daniel Kaufman, Gwendolyn F.M. Kestrel, Mike Selinker, and Skip Williams
A fortune of new hazards! Keep your players guessing (and ducking for cover) with the Book of Challenges, the new D&D directory of deception for devious DMs. Choose from over 50 ready-to-use, scalable encounters, or develop your own dungeon rooms, puzzles, and traps with advice from the pros. This excerpt offers a logic puzzle that could land unwary player characters in very hot water.
FIRE AND WATER (EL 7)
This insidious antechamber features a simple logic puzzle, along with a few creatures to keep things lively. It also presents a chance for characters to talk their way out of a fight. Groups that attack first and talk later should have a more difficult time than groups that only fight when they must. Of course, the PCs have a better chance for a successful negotiation if at least one of them has a decent Charisma score.
1. Antechamber (EL 4)
The antechamber's vaulted ceiling peaks at 18 feet, sloping down to 8 feet at the north and south walls. The masonry walls are crumbling slightly (Climb DC 15), but are otherwise intact. Sufficient handholds allow skilled climbers to gradually make their way across the sloping ceiling (Climb DC 25).
The grates cover 2-foot-by-2-foot vertical shafts that drop 30 feet to a drain below. The 3-foot-by-3-foot drain connects to the pyramid in area 2 (see diagram) and eventually leads to an underground lake or magma chamber.
Grates: 2 in. thick; hardness 10; hp 60; AC 6; break DC 25.
The south wall of the antechamber has five grille-covered niches about 16 feet from the floor, each holding a musical instrument (from west to east: a bell, a drum, a gong, a horn, and a whistle) hooked up to an apparatus capable of playing the instrument. Five grilles are set in the vault south of the peak, about 16 feet off the ground.
Grilles: 1 in. thick; hardness 10; hp 30; AC 6; break DC 23.
The portcullises are locked in place. Each is 10 feet wide and 12 feet high. Throwing the purple lever (see the Traps section) raises both portcullises. The portcullises have widely spaced bars. Tiny or smaller creatures can pass freely through the bars. A Small creature could use a move action to wiggle through them. Medium-size or larger creatures must break though the bars. The portcullises do not block spell effects, but if any attack passes through a portcullis (such as a ray attack), the target gains one-quarter cover (+2 cover bonus to AC, +1 cover bonus on Reflex saves).
Iron Portcullis: 2 in. thick; hardness 10; hp 60; AC 4; break DC 28; lift DC 28 (or DC 38 when locked).
As soon as the PCs make any noise or begin throwing levers in area 1, the mephits living in area 2 come to the portcullises to investigate (see Area 2, Tactics).
The Puzzle: The levers constitute both a puzzle and a trap. Each lever operates a feature in one of these rooms, as well as "playing" an instrument in its corresponding niche. The levers are slightly stiff, so it takes a Strength check (DC 13) to move one. Until the PCs pull the red lever, none of the other levers move at all.
The red lever unlocks the blue and purple levers. Each time it is moved, it sounds the gong.
The blue lever unlocks the yellow and green levers and empties the contents of the moat (but not the pyramid) in area 2 into the drain passage. Draining the moat requires 4 rounds, but during this time, a character can stop the process by pulling the blue lever again. Unless the red lever has been pulled, the blue lever remains locked. One minute after the blue lever is pulled, it automatically returns to its original position (which relocks the yellow and green levers and closes the drain from the moat). Each time the blue lever moves, it blows the horn.
The purple lever raises or lowers the portcullises. Unless the red lever has been pulled, the purple lever remains locked. Each time the purple lever is moved, it bangs the drum.
The yellow lever opens and closes the sluices leading from the pyramid to the moat in area 2. Unless the blue lever has been pulled, the yellow lever remains locked. Each time the yellow lever is moved, it rings the bell.
The green lever empties the lava from the pyramid (but not the moat) into the vertical drain passage, as indicated in the diagram. Emptying the pyramid takes 1 minute. Unless the blue lever has been pulled, the green lever remains locked. Each time the green lever is moved, it blows the whistle.
If the water and the lava ever end up in the same place (either the moat or the drain), one of the two trap effects below occurs. To get at the treasure, the PCs must move the water into the drain and the lava into the moat.
The optimal order of operation of the levers is as follows: red (unlocks blue and purple), purple (opens portcullises), blue (unlocks yellow and green and empties the water from the moat), and yellow after the moat drains close (empties the lava from the pyramid into the moat). This gives the PCs access to the treasure concealed within the pyramid. However, it is unlikely that the characters stumble upon this the first time through (see Treasure, below, for some hints that might help them).
Hints: An Intelligence check (DC 15) suggests the puzzle is a logic puzzle of some sort. A Search check (DC 15) indicates that the levers cause parts of the moat and pyramid to move; a dwarf's stonecunning ability adds +2 to this check. A Disable Device check (DC 20) determines that some levers will not move until others do.
Trap: If the PCs pull the yellow lever while the moat contains water, a cloud of vapor belches forth, spreading 20 feet from the moat and throwing up bits of debris and chunks of hardened lava. On the first round, it deals 2d6 points of bludgeoning damage to anyone caught in the blast. Each round thereafter, the cloud spreads an additional 10 feet and deals an additional 2d6 points of fire damage. This cloud stops expanding and fades away 1 round after lava stops pouring into the moat (when the PCs throw the yellow lever again or after 1 minute).
Lava Trap: CR 4; no attack roll necessary (20 ft. spread plus 10 ft./round; 2d6 points of bludgeoning damage first round, +2d6 points of fire damage each additional round); Reflex DC 15 half.
Trap: If the PCs empty any water from the moat (blue lever) after they empty lava from the pyramid (green lever) or vice versa, the water hits the lava in the drain and turns into superheated steam. The PCs immediately hear and feel a rumble beneath their feet. One round later, geysers of steam shoot from all gratings in areas 1 and 2. This functions similarly to the lava trap (including the expanding clouds), but without any debris. Multiple overlapping clouds don't inflict extra damage. The clouds stop expanding and fade away 1 round after the water stops emptying into the drain (either because the water ran out or because the PCs threw the blue lever again). It takes 4 rounds to drain all the water from the moat.
Steam Trap: CR 3; no attack roll necessary (10-ft. spread plus 10 ft./round; 2d6 points of fire damage each round); Reflex DC 15 half.
These traps can't be discovered with a Search check, nor can they truly be disabled; however, a successful Disable Device check against DC 20 can jam a lever in place, rendering it inoperable until a similar check frees it up.
Treasure: The charred bodies are all that's left of a pair of adventurers who tried to tackle the trap a little over a year ago without first dealing with the mephits in area 2. The mephits have looted the bodies, but one of the corpses is clutching a scroll containing a few notes (see sidebar). These form a logic puzzle that might allow characters to determine what the levers do and in what order they should be thrown.
According to the scroll, a secret compartment under the lava holds a ring once owned by Hawrence de Rasor. A successful bardic knowledge or Knowledge (arcana) check (DC 25) reveals that he was a fairly obscure wizard who wrote several treatises on logic.
The corpses are just complete enough to allow a speak with dead spell to work. However, they know nothing except whatís on their list of clues (the scroll). A treasure map they found had directions to this room and the list of clues. If asked about their deaths, the corpses warn the PCs about the "vile fire creatures" living in the pyramid.
2. Pyramid Chamber (EL 6)
When the PCs look though either of the portcullises, read the following text.
This chamber is similar to area 1, except that its vaulted ceiling is 80 feet high at the center, sloping down to 45 feet, where it meets the walls.
A 10-foot-deep moat surrounds the 40-foot-high pyramid. The pool of lava at the pyramid's top is 20 feet deep. It contains some volatile elements and is covered in flames. Touching the lava or the flames deals 2d6 points of fire damage each round. Immersion in the lava deals 20d6 points of fire damage each round.
The nearly sheer walls of the pyramid are made of superior masonry. If the PCs don't want to mess with the levers in area 1, they can just make a hole in the top of the pyramid and release the lava that way. If they do so, they're likely to dump the lava into the moat and create a cloud of scalding steam (see the steam trap in area 1).
Superior Masonry Walls: 3 ft. thick; hardness 8; hp 270; AC 3; break DC 59; Climb DC 20.
A fall into the 10-foot-deep moat deals no damage if the moat is still full of water (though the victim may eventually drown). The character suffers 1d6 points of damage if the moat is empty, or 20d6 points of fire damage each round if it is full of lava.
Creatures: Three mephits -- a fire mephit, magma mephit, and steam mephit -- lair at the top of the pyramid. The mephits think of themselves as the supreme overlords of the chamber and the masters of all they survey. They donít take kindly to adventurers wandering in to drain off the lava. They spend most of their time floating on their backs in the lava pool. The pool has a rim about 6 inches high. The characters can't see the mephits from area 1 or from floor level in this chamber.
Over the years, the mephits have discovered the trapdoor at the bottom of the lava pool, but they have never been able to open it with the lava still in place. They also suspect (correctly) that opening the trapdoor and letting in the lava would probably destroy anything stored underneath the door.
Tactics: When the mephits hear people talking or fiddling with the levers in area 1, they fly to the portcullises. They then demand to know what the interlopers are doing: "Cease your feeble efforts, unworthy ones! We, the Triumvirate of Fire, command you to leave -- or face our scorching wrath!" The mephits deliver their challenge in Common but speak to each other in Ignan.
The mephits begin with an unfriendly attitude (see NPC Attitudes in Chapter 5 of the Dungeon Master's Guide). If the PCs alter this to indifferent, the mephits agree to "sell" the PCs their lava pool for the sum of 250 gp per mephit. If the PCs adjust their attitude to friendly or better, the price drops to 150 gp per mephit. If the PCs don't have enough cash, gems, or jewelry to satisfy the mephits, they accept double the value in goods instead. The mephits accept only useful things, such as magic items, in trade. The mephits are susceptible to flattery. Characters who treat the mephits like the rulers they claim to be, or who praise them for their awesome power, receive a +2 circumstance bonus on Diplomacy or Charisma checks to alter their attitudes.
If the PCs attack or ignore the mephits, the creatures use their breath weapons and spell-like abilities on any target within range. Because the mephits can stick their heads through the portcullises, the PCs gain no cover bonus on their Reflex saves against the breath weapons. They don't hesitate to summon other mephits (25% chance of success).
The fire mephit uses heat metal on the levers to discourage the PCs from operating them. The magma mephit shapechanges into a pool of lava and oozes through a portcullis, attempting to ignite unwary PCs. If it starts a fire, it uses pyrotechnics to create blinding fireworks. The steam mephit rains boiling water down on PCs who remain near a portcullis.
The magma mephit gains fast healing 2 when in contact with the lava pool. The fire mephit requires a torch-sized flame to activate its fast healing, while the steam mephit gains fast healing in any hot, humid area (such as this chamber, if the PCs have mixed water with lava using the levers).
Treasure: After the PCs deal with the mephits who live here and drain off the lava, they can find the secret trapdoor (Search DC 20) in the northwest corner of the top of the pyramid. This conceals a small compartment that holds a ring of wizardry (I).
Scaling the Challenge
Designing Logic Problems
Design a logic problem as you would solve one: Winnow down many possibilities to one correct answer. A simple logic problem requires making sense of a single complex statement of relationship. Figure out what relationship you want between the elements in the problem. Find a roundabout way to describe the relationship. Then test all possibilities until you're sure only one can be right.
A more complex logic problem such as the one in this encounter involves multiple statements of a complex relationship. Think of what the logic puzzle will be about, and then select some appropriate variables on which the puzzle will turn. For the puzzle here, the elements are the colors (like blue), the activities (like raising the portcullis), and the sounds (like the gong).
Then lay the possibilities into a solving grid allowing for all the possibilities to meet each other (in this case it's color-and-activity, activity-and-sound, and color-and-sound). Here's one version.
Write clues that eliminate possibilities for the solver until only the right answers remain. As you build clues, eliminate and confirm possibilities in the grid. Eliminated possibilities get an X, while confirmed possibilities get an O. So, the statement "The red lever drains the moat and does not make a gong sound" places an O at the intersection of "red" and "moat," an X at the intersection of "red" and "gong," and an X at the intersection of "moat" and "gong." Because this sample is so small, this single clue can fill in the entire grid shown, but with more choices, more clues will be needed. Try to get the clue list down to the smallest number of clues possible, double-check the grid, and give the puzzle to your players (with or without the blank grid, depending on how nice you feel).
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