Underground Tunnels (Wandering Monster Tables)

Far beneath much of the snowy lands on Nyssa, is a wide geography of tunnels where huge swaths of civil and uncivil races reside. They fight, plunder or hunt, looking for lost magic, treasure and weapons - trying to gain an edge before another group does them in. Just as often it is adventurers from above, as monsters from below. Allies can be made, but assume most things you meet will try to kill you.

Many non-adventures assume everything is controlled by the Lizardith or Lizard men city-nations. 
While they certainly have the largest individual mass, and the most numbers, they tear each other apart just as quick as attack strangers from anywhere. 

Monsters are found in the Pathfinder Monster books I - V, as well as my own beasties, some  left overs from 3.5 edition and other books.

In most dungeons I do an approximate 50-50% breakdown of set creatures and wandering monsters. 
For example in Rooms A, C, E, & F there may be known creatures or situations that the party will most likely interact with. In the other places - Rooms B, D, G - I roll a wandering monster check. Then anytime the party makes significant noise, rests, disturbs the area, etc roll the +/- chance as normal.

Base Chance: 3 / 20 base likelihood.  Add +1 for every missed opportunity. After a hit, reduce by half but never lower than base. 

Otherwise, use the table as you see fit. 

Underground Wandering Monster Table

1. Adult White Dragon               CR 10 PF 1 

2. Omox                                      CR 12 PF 3

3. Neothelid                                CR 15 PF 1   
4. Roper                                      CR 12 PF 1

5. Cave In     (25% something in the debris is useful)

6. Azruverda                               CR 13 PF 2

7. Gorazagh                                CR 13 PF 2

8. Mihstu                                     CR 8  PF 3

9. Vemerak                                  CR 14 PF 3

10. Giant                                     CR 10 PF 1

11. Destrachun                            CR 8   PF 3

12. Deathtrap Ooze                     CR 8   PF 2

13. Caulborn                               CR 7   PF 2

14. Chaos Beast                          CR 7   PF 3

15. Statue     (# 2d4; Reroll to Monster or Humanoid Type)                   

16. Gug                                      CR 10 PF 3

17. Black Pudding                      CR 7  PF 1

18. Civilized Contact (See Subrace Table Below)

19. Shard Slag                            CR 8 PF 4

21. Dire Bear                              CR 7 PF 1

22. Cerebrc Fungus                    CR 3 PF 2

23. Brain Ooze                            CR 7 PF 2

24. Disenchanter Snake              CR 3 PF 2

25. Abandoned Campsite (25% something in the debris is useful)
26. Myceloid                                CR 4 PF 2

27. Adherer.                                 CR 3 PF 2

28. Ascomid                                 CR 5 PF 2

29. Diplomatic (See Subrace Table Below)

30. Belker                                     CR 6 PF 3

31 Amphisbema                           CR 4 PF 3

32 Blood Hag                               CR 8 PF 4

33 Blindheim                               CR 2 PF 3

34 Iron Salamander                      CR 5 PF 1    

35 Stalactites # 2-16 (Reroll to determine if anything is hiding, DMs discretion if not usable)

36 Crysmal                                  CR 3 PF 3

37 Dark Ones                               CR 2+ PF 3

38 Decampus                               CR 4 PF 3

39. Magma Elemental                 CR V PF 3

40. Mud Elemental                      CR V PF 3

41. Faceless Stalker                     CR 4 PF 3

42 Fungal Crawler                       CR 3 PF 3

43. Tarantula Giant                      CR 8 PF 3

44 Grick                                       CR 3 PF 3

45 Pit (see below)

46. Ogre                                        CR 3 PF 1

47. Pech                                        CR 3 PF 3

48. Phycomid                                CR 4 PF 3

49. Sandman                                 CR 3 PF 3   

50 - 51. Patrol (See Subrace Table Below)

52. Seagathi                                  CR 5 PF 3   
53. Slithering Tracker                   CR 4 PF 3        

54. Slur                                         CR 2 PF 3

55. Petrified Mushrooms # 2-16 (Reroll to determine if anything is hiding, DMs discretion if useful)

56. Rock Troll                               CR 4 PF 3  
57. Buggane                                  CR 5 PF 4

58. Beholder, Lesser Nyssian       CR 6  (Six eyes)

59. Fungal Beast                           CR 4 PF 4

60. Graeae                                     CR 5 PF 4

61. Lampad                                   CR 5 PF 4

62. Lurking Ray                            CR 4 PF 4

63. Mudlord                                  CR 6 PF 4

64. Nightgaunt                              CR 4 PF 4

65. Stone Stairs (70% Up, 30% down)

66. Shriezak                                  CR 4 PF 4

67. Animated Object                     CR 6 PF 1 (reroll on object table)

68. Lesser Barghest                       CR 3 PF 1

69. Basilisk                                   CR 5 PF 1

70. Cave Fisher                            CR 2 PF 1

71. Choker                                    CR 2 PF 1

72. Cloaker                                   CR 5 PF 1

73. Cyclops, Kabandha                 CR 9 PF 5

74. Gelatinous Cube                     CR 3 PF 1

75. Shrine / Obelisk / Burial Site    (50% something useful at site)

76. Gray Ooze                              CR 4 PF 1

77. Kyton                                      CR 6 PF 1

78. Mephit                                    CR 3 PF 1

79. Mimic                                     CR 4 PF 1 (reroll on object table)

80. Trader (See Subrace Table Below)

81. Morlock                                   CR 2 PF 1

82. Ochre Jelly                               CR 5 PF 1

83. Otyugh                                     CR 4 PF 1

84. Rust Monster                           CR 3 PF 1

85. Pool of Water  (80% bad stench)

86. Giant Scorpion                        CR 3  PF 1

87. Shadow                                    CR 3 PF 1 

88. Gibbering Mouther                  CR 5 PF 1 

89. Gorgon                                     CR 8 PF 1

90. Caller in Darkness                   CR 9  PF 5
91. Greater Barghest                      CR 7 PF 1

92. Medusa                                    CR 7 PF 1

93. Dark Naga                                CR 8 PF 1

94. Intellect Devourer                    CR 8 PF 1

95. Waterfall  (01-30% hiding monster, 31-70 reroll for hidden monster; 71+ hidden passageway) 

96. Undead (See Subrace Table Below)

97. Ghoul, Leng                            CR 10  PF 5

98. Denizen of Leng                      CR 8  PF 3

99. Purple Worm                           CR 12 PF 1

100. DM's Choice


Pits are usually 20-80 feet deep and covers most of the width of the cave. (Reroll to determine what's inside the Pit) or 5% Reverse Pit (Fall Up to the ceiling; 50% dmg base)

When a general type of monster is found, use the sub-race table and description listed below for purpose. A DM can pick as needed or use the default mentioned by asterisk (*).  

Hunting Patrol           Commerce                           Diplomatic

2. Human                     2. Axomite                           2. Jackalla *

3. Jahlen                       3 - 4. Dwarf *                      3. Mongrelman

4 - 6. Lizardith *          5 - 6. Troglydyte                  4. Corlth

7. Derro                        7. Human                             5. Trox

8. Dwarf                       8. Corlth                               6. Human

9. Clockwork               9. Goblin                              7. Dwarf

10. Trox                       10. Lizardith                         8 - 9. Lizardith

11. Goblin                    11. Corlth                             10. Goblin

12. Minotaur                12. Mercane                         11. Troglydyte

12. Ratling                   13. Ratling                           12.  Azer
                                     14. Azer                               13. Ratling
                                     15. Axomite                        14. Samsaran
                                     16. Shabti                            15. Minotaur      

                                                                                 16. Caligni 

   

Civilized                       Crypt                                 Common Underground Object  

2. Skum                       2-3.  Shabti                           2. Small Statue
3. Troglydyte               4. Crypt Thing     3. Wheel

4 Corlth                       5 .  Restless    4. Debris (Usually Mechanical)

5. Flumph                    6-8. Cadaver *  5. Broken Weapon

6. Mongrelman            9.   Lesser Mummy              6. Broken Armor

7. Goblin                     10.  Wight                             7. Busted Barrel    
8. Derro                       11.  Wraith                            8. Boxes       

9. Human                     12.  Shadow                          9. Broken Camping Gear   

10. Lizardith                13   Festering Spirit              10. Animal Carcass 

11. Minotaur                14. Samsaran                        11. Iron Rations (40% Stale)

12. Azer                       15 - 16 Jackalla                    12. Beer, Barrel or Bottle  

13. Ratling *                                                              13. Wine / Alcohol Bottles  

14. Sinspawn                                                             14. Bundles of Rope     

15. Oread                                                                   15. Candles or Torches  2-4 

16. Changeling                                                          16. Ornamental Decoration / Holy Symbol     

17. Trox                                                                     17. Climbing Gear      

18. Samsaran                                                             18. Broken Mirror      

19. Axomite                                                               19. Unidentified Corpse

20. Mercane                                                               20. Burnt Lamp     
21. Caligni                                                                 21. 50% One Boot; 50% two good boots
22. Ghoran                                                                 22. 2 silver arrows OR daggers (DM`s choice)
23. Shabti                                                                   23. Magical Potion
24. Jackalla                                                                 24. Coin Purse (1d00 silver pieces)
                                                                             
Hunting Patrols: 2-8 individuals, with typical weapons for the race in question. 10% likelihood they are returning home. May provide a +/- 2 on next roll if they are engaged in conversation or bribed via any social skill interaction the DM feels appropriate (Social DC 15).

Commerce: 11-20 people, with trading gear. Half the travelers are defenders. Most groups have a way to hide or protect themselves. 20% likelihood they are returning home. May provide a +/- 3 on next roll if they are engaged in conversation or bribed. (Social DC 18)

Diplomatic: 9-16 people who have arranged to make a meeting to discuss peace. will have 25% or more of spell casters. 33% likelihood they are returning home. May provide a +/- 2 on next roll if they are engaged in conversation or bribed. (Social DC 16)

Civilized: 23-80 individuals, inhabiting a small settlement. 10% chance they will have trading supplies. May provide a +/- 4 on next roll if they are engaged in conversation, have able goods or bribed. (Social DC 13)  

Crypt: 2-8 individuals. Most are lost, hungry or otherwise purposeless, rarely a direct threat to other groups unless the party seems very weak. Undead groups often come from another common groups found in the same region - often they don`t even realize they are dead. Many travelers simply leave any undead they find without interacting with them unless absolutely necessary. Samsaran are living creatures that automatically reincarnate (one time) from dead corpses- they come to crypts to look for guidance. Shabti are former wealthy people who paid for resurrection. Jackalla are undead hunters.