Node Mapping the Underdark
The GM map is just a node map showing each site/intersection as a node with the paths leading away from it connected visually in their respective position on the compass rose (i.e. North = up, South = down).
If at any point when mapping an area, if there are at least 6 passages unexplored, the next area will be a dead end on a d6 roll of 6+. (DM may modify this by up to +3 depending on circumstances)
Unless otherwise specified by the location or site, for each node, roll 2d4 to get the number of passages that connect to the node. If node is a settlement with unspecific exits, add 2 to this roll with a max of 8 exits. Each node is one of the locations on the map. For each passage that connects to a node, roll 1d8 to determine the cardinal direction the passage enters/exits the node from with North = 1, NE = 2, etc. Start with which the route the party enters the node.
In general, it is best to have at least two nodes between Sites/settlements. If a Site/Settlement option is rolled, instead have a ruin or creature lair (whichever is more appropriate given surroundings) and the next appropriate node is automatically a Site/Settlement. First Cavern counts as a settlement for this purpose.
Endless Cavern nodes are anywhere from 400 yards to a mile on a side while the passages are, on average, about 75 yards wide and generally no more than 200 yards wide at any given point.
When a passage is taken for the first time, roll 1d4+1d6-2, minimum 1 (1-8 with the probablity being highest of 3-5 – source:http://anydice.com/program/58ca) to determine the distance in miles to the next node.
|1||just an intersection, roll an extra encounter check|
|2||just an intersection, nothing else of note|
|3||intersection with a creature lair, roll on Creature Chart to determine type|
|4||new Site or Settlement, roll on Sites & Settlements Chart|
|5||new Location, roll on Location Connections Chart|
|6||previously discovered Endless Caverns node; determine randomly|
Each labyrinth node is an area 100-200 yards on a side. The passages are about 15 yards wide.
After rolling for connecting nodes, roll 1d8 for each and on a 3+, the node continues in that direction rather than just being a passage – treat the new node as any other as far as determining passages/node continuation. (max 2 new extensions per node. I.E. node A rolls 2 3+ to extend into Nodes B and C, node C rolls 3 3+s but can only extend 2 times into nodes D & E where we would roll again and node B rolls 1 3+ so it expands into node F and rolls again)
When a passage is taken for the first time, roll 1d4+1d6-2, minimum 1 to determine the distance in tens of yards to the next node. Any time a passage goes in the direction of a known node that has no exit in that direction, the passage is a raised passage over the old.
|4||as 1, 2, or 3 with a creature’s lair; roll on Creature chart to determine what|
|5||new Site or Settlement; roll on Sites & Settlements chart|
|6||new Location; roll on Location Connections chart|
Random Encounters when travelling
See the chart below to determine how many Encounter Checks to roll between nodes. For each check , roll a 1d6 and on a 6+, an encounter happens (at the DM’s prerogative there may be an addition to the roll of up to +3 based on circumstances). Then roll on Encounter Chart to see what is encountered
|1-2||spoor/sign – roll d6: 1-2 random civ, 3-6 wild creatures|
|3||patrol of random civilization roll on Random CIv chart|
|4-5||wild monster(s) roll on wild creature chart|
|6||Resource cache (such as a vein of ore or abandoned cart of cloth)|
|Roll||Endless Caverns||Labyrinth||Fungal Fields||Glittering Caves||Grand Chasm||Great Undersea||Freshflow River|
|1||cthaka goblins||cthaka goblins||Goska goblins||Lagdush orcs||ushad kobolds||cthaka goblins||Muzga Lizardfolk|
|2||goska goblins||Shakil Lizardfolk||anvilhold dwarves||rakand ogres||anvilhold dwarves|
|hagga goblins||Gorlutz orcs||lagdush orcs|
|Chapel||Black Friars||gurak||muzga swamp creatures|
|Fungal Field||grand chasm||glittering caves||fungal fields||great undersea||freshflow river||great undersea|
|Glittering Cave||endless caverns||endless caverns||endless caverns||endless caverns||grand chasm|
|Endless Caverns||Labyrinth||Glittering Caves||Fungal Fields||Freshflow River||Grand Chasm|
|ruin||Pillar of the Black Friars||First Landing Mineshaft||Goska||Muzga Island||Ushad|
|The Clockwork Tower||Islington’s Lair||Anvilhold Mineshaft||Shakil||Anvilhold Landing||Rakand|
|The Chapel of All Deities||roll 1d10, on 10 – find Hermit’s Hut||Lagdush||Gorlutz||Lagdush Docks||Gurak’s Lair|
|The Winding Stair (Grand Chasm)||Grand Chasm||Endless Caverns (multiple)||Glittering Caves||Freshflow River Delta (Great Undersea)||The Winding Stairs (Endless Caverns)|
|Grand Chasm Midway||Endless Caverns (multiple)||Fungal Fields||Endless Caverns||Midpoint Cave (Endless Caverns)|
|Labyrinth (multiple)||Fungal Fields||Labyrinth||Labyrinth Entrance|
|Glittering Cave (multiple)||Undersea Shore|
|4||abandoned cart of (insert resource)|
|5||Dead bodies of (insert two civ/creatures) around pile of (insert resource)|