I kit-bashed a version of exploration rules that were highly customized for the 4 players in my
Tomb of Annihilation campaign during their search of the ruined city of Omu – their goal was acquiring 9 puzzle cubes from shrines scattered across the ruins. These rules worked well for us in that circumstance, and it probably was the most interesting / least tedious procedural exploration experience I've had in RPGs. I liked them so much, I would adapt a similar customized approach were I to run a mega-dungeon game.
The point of this was to weave the backstory of Omu and foreshadowing of other campaign elements into the exploration process to build suspense, mystery, and sense of discovery.
Time was a factor due to a rival party of Red Wizards taking actions to thwart PCs' efforts in the ruined city, and a night hag hunting adventurers in the ruins at night.
This was a mix of my own material, material from blogs/ENWorld,
Tomb of Annihilation of course, and Sean's excellent
Tomb of Annihilation Companion.
Exploring Omu
Each hex = 250 feet, representing very difficult terrain due to ruined buildings and natural overgrowth.
Moving Cautiously you cover a hex in 5 minutes, and your party can make Stealth checks.
Moving Normally you cover a hex in 2.5 minutes.
Moving Quickly you cover a hex in 1 minute, but your party lookout(s) suffers -5 passive Perception.
Searching a hex thoroughly requires 30 minutes.
While adventuring in Omu, there are
Exploration Roles you may wish to divide among your party:
- The Investigator searches for clues and treasure; make an Investigation check upon entering a new unkeyed hex.
- The Lookout keeps an eye out for sneaky monsters and traps; you can use your passive Perception while exploring (PCs with other roles may not). When entering a new hex without keyed areas, there’s a 10% chance for random encounters (d12).
- The Mapper handles annotating your map of Omu; the DM may call for checks to deduce locations. When entering a new hex without keyed areas, there’s a 50% chance of finding an interesting ruined structure (d12).
- The Scout scouts out an adjacent hex; making a Perception check in new unkeyed hexes or a Stealth check in new hexes with keyed areas.
- Optionally, the Tracker locates a specific monster/NPC, or there may be other player-created roles.
Investigator (draw a card)
Searches for clues/treasure. Make an Investigation check in each hex explored, with results determined by the DC attained.
DC 21+: Find a clue about the Tomb’s construction (
d8):
1 = Old papyrus engineering documents stamped by “Gorra” for a massive skeleton door with five geometric keyholes.
2 = Water-damaged dinosaur hide journal with etchings of 9 puzzle cubes and illegible warning about “the false entrance”.
3 = Urn with engravings depicting the mass sacrifice of gorgons to harvest their blood to make mortar used.
4 = Royal edict on clay tablet proclaiming the Devourer seeks Omu’s five best gamblers to challenge him to a game of dice and the winner will earn freedom (five worn names surrounded by polyhedral silhouettes: triangle, square, pentagon, hexagon, octagon) and a set of magic chrysoprase gems.
5 = Dwarven stone pattern roller with hidden message lamenting vast amounts of diamond dust used in creating the Tomb of the Nine Gods that depleted all of Chult’s diamond mines.
6 = Holy symbol of Ubtao enchanted with magic mouth speaking in Old Omuan: “The Devourer has killed our gods and outlawed worship. No amount of divination pierces the unhallowed Tomb where my kinsmen toil. Ubtao save us."
7 = Star chart depicting constellations of the Nine Trickster gods moving around the constellation of a flail snail which always remains at the center.
8 = Seemingly mad arrangement of floor tiles with Omuan letters are actually an anagram: The Tomb is Gone Neared End / Evil Breath Whenever Guilt / A Foul Eye Inherits Thy Tumor (answer: The Nine Gods are entombed 3,4,4,3,8/ But will have their revenge 3,4,4,5,7/ If you let them in your hearts 2,3,3,4,2,4,5)
DC 16-20: Helpful Graffiti (
d8) and/or an Omuan art object (
d8):
1 = black and silver painted pottery (25 gp);
2 = silver-inlaid wooden statuette of a trickster god (100 gp);
3 = jade ring (250 gp);
4 = vase holding 100 gp of diamond dust;
5 = bismuth crystal dragonchess set made in likeness of Omuan royalty (500 gp);
6 = ivory funerary urn inlaid with amber entrapping wasps (1,000 gp);
7 = gold music box playing creepy song (5,000 gp);
8 = scroll case with map of small section of city as it was in its heyday (2d4 hexes keyed locations).
DC 11-15: Insane Graffiti (
d8) and/or a Chultan Trinket (
d100).
DC 10 or less: Disturb (
d8): 1-2 = 2d6
stirges, 3-4 = 1d6
giant wasps, 5-6 = 1d3
swarms of poisonous snakes, 7-8 = 1d6
giant wolf spiders.
Lookout
Use the passive Perception of any PCs looking out for detecting sneaking monsters and trap triggers. When entering a hex without keyed areas roll 10% chance of a Random Encounter (d12).
Mapper
Can make notations on the vinyl Omu map and DM may call for Intelligence (cartographer’s tools) check to deduce locations. When entering a hex without keyed areas roll 50% chance of an Interesting Ruined Structure (d12).
Scout
Chooses an adjacent hex and if it is unkeyed make a Perception check, but if it has keyed areas make a Stealth check instead.
Perception
DC 21+: What do you want to know?
DC 16-20: You learn of keyed areas and any interesting ruined structures in the hex, the numbers and exact nature of any random encounters, and hints of traps/hazards.
DC 11-15: You learn of keyed areas and any interesting ruined structures in the hex, and whether or not random encounters (possible clues indicating creature type, though not their exact nature).
DC 6-10: You learn of keyed areas in adjacent hexes
DC 5 or less: You gain no valuable reconnaissance.
Stealth
DC 21+: You are completely unseen and scout enough for your party to be able to make group Stealth to ambush.
DC 16-20: You are completely unseen.
DC 11-15: You are spotted by a few creatures, which go on alert but do not pursue.
DC 6-10: You are spotted by most creatures, which give pursuit (without sounding alarm).
DC 5 or less: You are spotted by all creatures, they go on alert, and organize pursuit.
Long Rest - Time Pressure
Peggy Deadbells uses Nightmare Haunting on the PCs. And 10% cumulative chance per day that Red Wizards solve a shrine and collect another Puzzle Cube.
(10%) Random Encounters (d12)
Replace a previously rolled encounter with 3
frost giants on/after Day 69 (the 90th day of Death Curse)
- Help from a backup PC or an allied NPC (d10): 1-Brendan’s backup, 2-Jesse’s backup, 3-Morgan’s backup, 4-Nik’s backup, 5-E’kama’s trail signs marking safe hex, 6-mist dragon sent by Pallas clears any mad monkey mists / gas hazards, 7-defaced graffiti about tomb’s false entrance left by Dragonbait, 8-Artus Cimber spots signs of Ras Nsi’s handiwork hinting that he’s behaving desperately, 9-Salida finds Helpful Graffiti, 10-“River Mist” spots signs of the Red Wizards. Alternately, if PCs have attuned to the Eye or Hand of Vecna, this indicates Salleek has found them and attacks.
- 7(2d6) grungs and 1 grung elite warrior hunting and performing recon. They are eager to parlay with KOKO and escort her to see Chief Yorb at Nangnang’s Shrine (t).
- 14(4d6) zoblins* sent by M’bobo the zombie lord to find whereabouts/weaknesses of Ras Nsi and Artus Cimber – M’bobo can see through their eyes and speak through them, wishes to parlay with YARGLE.
- 5(2d4) gargoyles swoop down, two armed with a net, attempting to capture one character, but fleeing if half are killed. They preferentially attack aarakocra, flying creatures, and creatures climbing cliff walls.
- BAG OF NAILS: The mad tabaxi assassin convinced he's surrounded by evil shapeshifters and wildshaped druids.
- KAKAROL’S KOBOLDS: 3(1d4+1) kobolds and a kobold inventor, roll 1d6 for what they’re doing, 1d6 for what they say before fleeing, and 1d4 for how they sneakily retreat toward the Ruined Bazaar (T).
- RED WIZARDS: Red Wizard Dyrax (evoker) and 4 thugs are after a Puzzle Cube. Signal for help if attacked.
- SHADOW ELVES/OBELISK: A shadow elf enchantress, shadow elf duelist, and shadow elf hunter investigate fallout from interplanar spell duel between Valindra Shadowmantle (Alia teth Mihrael) and Acererak.
- ZALKORE’S REVENGE: A flooded backstreet with russet mold, a yellow musk creeper and 14 yellow musk zombies, 8 vegepygmies, as well as a shambling mound with face-engraved treasure chest for a head.
- KING OF FEATHERS: The King of Feathers*!
- DEADBELLS' GANG: Peggy Deadbells (night hag) hunting PCs with Captain Laskilar (bandit lord), Enoch Zefiri (gladiator), Wangrod (goblin assassin), and clay golem imbued with Semuanya’s life-spark. She waits till nightfall to use Nightmare Haunting or otherwise waits till an opportune moment to ambush. During the day she is alone (rest are on Ethereal) and disguised as River Mist; she claims to have guided the Red Wizards to Omu via the River Soshenstar (arriving Day 54) but to have since quit their company after they provoked a conflict with yuan-ti, tortured grungs & vegepygmies for information, and left her brother Flask of Wine for dead when they were separated. She's searching for her brother now. If PCs grow suspicious, she claims that Indigo sent them to find the Eye of Zaltec, a symbol of tabaxi oppression that Indigo wants to see destroyed in a move to gain the support of all tabaxi in Port Nyanzaru. “River Mist” accuses Salida of leading doomed expeditions, while Salida claims River Mist is the pocket of the Zhentarim.
- YUAN-TI: 5 yuan-ti malisons & 10 yuan-ti purebloods stage an ambush if 3+ Puzzle Cubes taken; otherwise watch.
(50%) Interesting Ruined Structures (d12)
- Abandoned Red Wizard Refuge. This ruin contains the remnants of a campsite for roughly a dozen people. Signs of a conflict litter the area including the bodies of Thayan mercenaries, guides of Port Nyanzaru, and badly decaying Batiri goblin corpses. Crude images of a stylized eye are drawn in chalk on the walls. A cracked silver mirror with arcane glyphs surrounding its edge used for scrying remains in the area. The broken mirror is worth 200 gold pieces.
- Access to Underground Sewers. Deep cracks in the basement of one of the ruins reveals access to narrow sewer passages that lead to various areas of Omu including the Royal Palace, the flooded rivers to the east, the Amphitheater, and the Walled Compound to the southwest. Traveling through the sewers has a 15% chance to encounter monsters. Use random encounter table level 5 to 10 swamp encounters in Xanathar's Guide to Everything: (69) giant crocodile, (27) 6 giant toads, (79) minute heavy rain extinguishing torches, (36) 60’ pit with 2 swarms of poisonous snakes.
- Altar to Dendar the Night Serpent. The ruins of this building contain a carving depicting a massive serpent eating its own tail surrounding a globe that looks like Toril. The rotting remains of a female dwarf lie on a bloody stone altar adorned with yuan-ti bones, her ritually dissected innards in a series of clay pots surrounding the altar; a DC 13 Wisdom (Medicine) check finds a faint snake bite at her neck and determines poison was the cause of death. Abyssal instructions on the pots describe a dark ritual involving feeding the innards to a creature in a prescribed order and then burning the creature alive to animate the bones of “Knassos, Master of Omu” (yuan-ti skeleton* of the abomination that died in the earthquakes which shook Omu 50 years ago).
- Ashen Court. This ruin contains bodies of ash still standing with looks of horror on their face. In the midst of a garden courtyard, the ashen body of a mother cradles her doomed child, and a crushed toy in the likeness of a chwinga lies on the ground. All of them appear to have been hit with a disintegrate spell, and touching causes them to crumble to dust. The garden contains 13(4d6) sinda berries on a bush and a menga bush with 2(1d6) ounces of menga leaves.
- Collapsed Cellar Shrine. The floor of a bakery has collapsed, stone ovens cascading into a cellar, creating a miniature waterfall when it rains. The cellar contains a small shrine to the “Lady of the Deadbells”, a sacrificial stone, and scrawlings in Old Omuan begging for mercy for a sick child. 5(2d6) zabou mushrooms grow among along the floor. A chwinga hops across the tops of the mushrooms.
- Crystal of Calling. The basement of this ruined building contains an arcane circle. In the center is a man-sized violet cracked crystal. A DC 14 Intelligence (Arcana/Religion) check reveals that the crystal was used by spellcasters to call across the multiverse, while DC 18 realizes this crystal was once used by the Eshowe. Any creature that touches the crystal can see visions of the Omuan priests and royalty using the crystal to call out across the Astral Plane, beseeching a new god to save them from their downfall, and then later witnessing the arrival of black star (sphere of annihilation) descending from sky and Acererak’s silhouette within.
- Desecrated Shrine to Ubtao. This ruin contains a shrine to the god Ubtao. The statue's head has been removed and lies in the corner covered in rubbish. Dark sigils have been etched into the statue's surface. Examining the sigils begins to fill the examiner's visions with the people of Omu destroying effigies of Ubtao after he turned his back on them two centuries ago. The cacophony of blasphemy fills the investigator's head with madness. The character must make a DC 14 Wisdom saving throw or suffer a short-term madness effect. Channel Divinity or hallow can be used to reconsecrate the shrine, gaining 1 Favor of Ubtao – which can be expended during a short rest to gain benefits of a long rest.
- Dwarven Gem-cutter. A gated courtyard is filled with mad monkey mists. On the far side is a gem-cutter’s workshop, though the door is trapped with wyvern watch (DC 22 Perception to notice insubstantial wyvern through mists): DC 17 Constitution save or paralyzed for 1 minute. The workshop is full of cutting and polishing tools, jars of acid, rocks, a notebook, and a magnifying apparatus. Among the scattered worthless rocks are 6x chyrosprases (50 gp each) and a black opal (1,000 gp). Notes in Dwarven reveal that a black opal crown was fashioned by a cult worshipping Dendar the Night Serpent, and that though the Omuan queen coveted the crown, the dwarf destroyed all evidence of it knowing such betrayal would cost his life.
- Noble Treasure Vault. A house of nobility has a trapped bronze door in the cellar guarded by 2 stone defenders (MToF). The door has two DC 15 glyphs of warding – one animates the “statues” and the other casts fear (30’, DC 15 or frightened of statues for 1 min, drop held items, and must take the Dash action and move away from statues by safest route on each of its turns, if the creature ends its turn in a location where it doesn’t have line of sight to you, the creature can make a Wisdom saving throw). If the trap is defeated, the PCs gain the noble house's treasury, including 832 cp, 3490 ep, 28 pp, 2x Chalcedony (50 gp), Citrine (50 gp), Jasper (50 gp), 3x Moonstone (50 gp), 5x Sardonyx (50 gp), 3x Zircon (50 gp), Potion of Resistance (thunder) (DMG 188), Potion of Water Breathing (uncommon, dmg 188), Spell Scroll (Sleet Storm) (DMG 200), and a Rope of Climbing (DMG 197).
- Ruin of Grasping Vines. Thick yellow thorned vines with withered brown flowers fill this ruined house seeming to come from a central stalk in the center that throbs like a heartbeat. The stalk itself (a yellow musk creeper with 99 hit points and a reach of 15 feet) grows from the ruins of the basement below and only there can it be truly destroyed. The remains of a pair of dead adventurers lies within the ruins, and searching the corpses turns up a Potion of Animal Friendship (uncommon, dmg 187) and a Potion of Growth (uncommon, dmg 187). 2d4 yellow musk zombies rise from the thick vines when someone enters (inkling of intelligence, Acererak can intermittently see through).
- Slave Pits of the Undercity. Crumbling earthen tenement housing once held slaves of varying sizes with tatterd carpets and faded wall carvings depicting the patchwork god Meriadar. Examining carpets finds plans for a rebellion woven into the weave-work, as well as thin layer of diamond dust (100 gp worth). As the PCs explore this structure, each must make a DC 12 Dexterity saving throw; the floor collapses under each PC who fails, dropping each PC 30-60 (1d4+2) feet underground. Beneath are ruined slave pits in which slaves were once forced to fight and were eventually buried; most of their bones have been exhumed.
- Trapped Incubus. The characters slide down 15-feet into a ruined pleasure den where the incubus Inamesi has been trapped for nearly a century within an inverted magic circle. Inamesi explains that he was trapped by the eladrin priest Hadarai who officiated over the trials of the Omuans, who intended to coerce Inamesi into service, but when Hadarai was cursed to become the King of Feathers, Inamesi was forgotten. He begs for release and will offer to share all he knows about Hadarai, tell the PCs about how the Omuans unwittingly invited Acererak, and the building of the Tomb of the Nine Gods by an embittered engineer (Gorra).
Graffiti
Helpful Graffiti (d8)
- (Chultan) The King hunts at night
- (Chultan) Obo’laka is in the East
- (Old Omuan) Trust not wizards bearing gifts
- (Old Omuan) Magnetite serves to test the worthy
- (Common) Trust the smell of honeysuckle (chwinga in Area #S/11 & Dragonbait tenderness or concern)
- (Common) Something is behind the obelisk
- (Common) The kobolds keep fixing the shrines
- (Common) Yuan-ti live below the palace
Insane Graffiti (d8)
- (Chultan) The Eye sees all
- (Chultan) Stay on the holy path
- (Chultan) Ubtao’s favor moves the moon and stars
- (Old Omuan) The city is dead already
- (Old Omuan) Beware the black star
- (Old Omuan) Feed the fire or we'll all be swallowed
- (Common) This place is safe now
- (Common) Grung are the key to everything
