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Subterranean

Note: Random encounters generated while adventuring underground tend to be of the combat variety more often than not since strange monsters often roam aimlessly about forgotten tombs, caves and dungeons. For me, random encounters are an important part of a classic "dungeon-crawl" and help add excitement to time spent underground.

Description: The following events are applicable whenever the PC's are traveling underground such as in a cave or dungeon.

Recommended Frequency: One time every two hours, whenever PC's travel more than 10 minutes, or whenever the GM desires.

Day Night
Die Roll Encounter Type
01-15 Potentially hostile encounter. Roll on Table 1 for the appropriate climate/terrain.
16-20 Unusual weather/terrain. Roll on Table 2 for the appropriate climate/terrain.
21-25 Notable Occurrence. Roll on Table 3 for the appropriate climate/terrain.
26-50 Travelers or non-hostile encounter. Roll on Table 4 for the appropriate climate/terrain.
51-00 No encounter.
Die Roll Encounter Type
01-30 Potentially hostile encounter. Roll on Table 1 for the appropriate climate/terrain.
31-35 Unusual weather/terrain. Roll on Table 2 for the appropriate climate/terrain.
36-40 Notable Occurrence. Roll on Table 3 for the appropriate climate/terrain.
41-45 Travelers or non-hostile encounter. Roll on Table 4 for the appropriate climate/terrain.
46-00 No encounter.

Weather or Terrain Event

As always, if a particular roll does not make sense or apply in your scenario, reroll or choose a better or more interesting one.

Event Effect
01-15 Cliffs
16-30 Hot/cold spot
31-32 Collapse from above
- Flood
33-47 Obscured View
- Fire
- Collapse from below
48-62
63-72 Wind blast
73-74
75-83
-
-
-
-
-
84-98
-
99-00

Dungeon (Low-Level) CR 2

d% Encounter Avg. CR
1–6 1d6 dire rats 1
7–12 1d6 fire beetles 1
13–20 1d6 human skeletons 1
21–24 1d4 giant centipedes 1
25–26 1 spider swarm 1
27–32 1d6 human zombies 2
33–34 1 choker 2
35–36 1 skeletal champion 2
37–44 2d6 goblins 3
45–48 1d4 ghouls 3
49–54 1d4 giant spiders 3
55–56 1 cockatrice 3
57–60 1 gelatinous cube 3
61–64 1 rust monster 3
65–68 1 shadow 3
69–70 1 wight 3
71–76 2d4 stirges 4
77–82 1d6 darkmantles 4
83–86 1d6 troglodytes 4
87–90 1d4 bugbears 4
91–92 1d4 vargouilles 4
93–94 1 gray ooze 4
95–96 1 mimic 4
97–100 1 ogre 4

Dungeon (Mid-Level) CR 5

d% Encounter Avg. CR
1–4 1 gelatinous cube 3
5–8 1 rust monster 3
9–16 2d4 stirges 3
17–22 1 gray ooze 4
23–26 1 mimic 4
27–30 1 basilisk 5
31–34 1 cloaker 5
35–38 1 gibbering mouther 5
39–42 1 ochre jelly 5
43–46 1 wraith 5
47–48 1 bearded devil 5
49–52 1d4 shadows 5
53–56 1d4 wights 5
57–62 1d8 skeletal champions 6
63–68 2d4 ghouls plus 1 ghast 6
69–72 1 ettin 6
73–78 1 minotaur 6
79–84 1d4 ogres 6
85–88 1d4 trolls 7
89–90 1 babau 7
91–94 1 black pudding 7
95–96 1 medusa 7
97–98 1 shadow demon 7
99–100 1d4 xills 8

Underground CR 9

d% Encounter Avg. CR
1–10 2d6 duergar
11–16 1d6 cave fishers
17–22 1 basidirond
23–32 2d6 drow and 1 drow noble
33–40 2d6 giant spiders
41–46 1d6 violet fungi
47–52 1d8 derros
53–60 2d6 morlocks
61–64 1 black pudding
65–68 1 giant slug
69–72 1d6 cloakers
73–82 2d6 dark creepers, 1 dark stalker
83–86 1d6 driders
87–90 1d6 intellect devourers
91–92 1 purple worm
93–96 1d4 ropers
97–98 1 neothelid
99–100 1 shoggoth

Dungeon (High-Level) CR 10

d% Encounter Avg. CR
1–4 1 black pudding 7
5–8 1 dark naga 8
9–14 1 mohrg 8
15–18 1 nabasu 8
19–22 1d6 cloakers 8
23–28 1d6 wraiths 8
29–36 1d4 ettins 8
37–40 1 bone devil 9
41–44 1 night hag 9
45–48 1 spirit naga 9
49–54 1 vampire 9
55–58 1 vrock 9
59–66 1d6 minotaurs 9
67–72 2d4 trolls 9
73–76 1d4 greater shadows 10
77–78 1 bebilith 10
79–82 1 barbed devil 11
83–86 1 devourer 11
87–88 1 hezrou 11
89–92 1d4 rakshasas 12
93–94 1 lich 12
95–96 1 glabrezu 13
97–98 1 ice devil 13
99–100 1 nalfeshnee 14

Subterranean Encounters

%d Result
01-08 NPC adventurers: 1d8 adventurers; roll on table 8-1 to determine party composition if desired.
09-32 Traders/caravan: One or more merchants transporting goods. Roll on table 8-2 to determine composition.
33-57 Hunting party (food): A group of 1d8 people out hunting game for food. Members are 1st level for shallow encounters, 3rd level for deep. They are led by a ranger or barbarian of 4th level if shallow, 6-8th level if deep. Note that they may consider PCs a good food source.
58-64 Scouts: A group scouting for a community located 1d20 miles away. They will attempt to observe the PCs but avoid a confrontation. The group consists of 1d6 members, each a ranger or rogue of up to 4th level for shallow encounters, 3rd-8th level for deep encounters.
65-68 War band: A military force out to loot and pillage. Consists of 3d20 common members (War1 if a class is needed), led by one first level fighter, ranger, or barbarian per five members, one 3rd level fighter, ranger, or barbarian per ten members, and one fighter, ranger, or barbarian war leader level 5-7. Group is 1% likely per member to have a Clr3 or Adp3, and 1% likely per member to have a Wiz3 or Sor3.
69-76 Foot patrol: Soldiers or militiamen keeping the trade routes safe. 3d6 common soldiers, two 2nd level lieutenants, and a 4th level leader.
77-84 Mounted patrol: Soldiers mounted on giant lizards, riding spiders or the equivalent. There are 2d8 common soldiers, one 3rd level lieutenant, and one 5th level leader; bump these levels up by +2 to +3 each if a deep encounter.
85-92 Brigands: A semiorganized band of 2d10 first level rogues and warriors, led by a single leader (roll on table 8-1 to determine leader’s class and level). Increase levels by +2 or +3 if a deep encounter.
93-00 Slavers: 4d6 slaves in chains guarded by 2d4 first level warriors and 1-3 3rd level lieutenants. Group is led by an expert level 3-6.