D&D 5E How to make an awesome Underdark encounter table in 5e?

[Quickleaf]

I'm running an Underdark exploration game for a couple friends via Roll20. Our approach is very improvisational and down the line we may rotate DMs, though for now I am in the hot seat. Anyhow, for a whole host of reasons, I want to have an awesome encounter table(s) that I can draw on during their ventures in the Underdark.

I welcome any and all input. Links, random encounter seeds, gaming resource suggestions, anecdotes -- it's all welcome

I have been inspired by Wrath of Zombie's Encounters in the Underdark and by Ivan Cannon's Wandering Monster Tables. However, I will be incorporating reaction rolls of some kind as well as "flavor"/non-combat encounters to present the Underdark more holistically.

Part 1: Narrowing it Down
The Underdark is divided into 3 parts in D&D lore: Upper, Middle, and Lower. It gets more dangerous the deeper you go. I'm going to roughly map these divisions to 5e' tiers of play: Upper (1-4), Middle (5-10), and Lower (11-16). Since we're starting at 1st level, I'm going to start by focusing on the Upperdark.

Later on I could see expanding to the Middledark and Lowerdark, possibly using nested tables similar to Ivan Cannon's (see above). But that's down the road.

Part 2: Conceptual Organization
I'm seeing the table as being 1d100 based, since they're going to be spending most of the game in the Underdark. While the monsters will probably be individual entries, I also think some things will be better handled as sub-tables: Dungeon Hazards, Underdark Animals, and Underdark Fungi/Plants, for example.

Part 3: Upperdark Monster Lists
I found a blog with a great list of monsters by layer of the Underdark. Interestingly, these monster lists also differentiate according to whether it is a Settled or Frontier region of the Underdark...not all the entries make sense to me, but it might be a useful distinction. I'll list the monsters below, with their CR after them; monsters that aren't in the 5e MM I will italicize (they don't have CRs obviously).

[SBLOCK=Monsters, Settled]
Allip
Boggle
Baneguard
Baphitaur
Barghest
Basilisk 3
Beholder, gauth
Bugbear 1
Carrion crawler 2
Centipede, giant 1/4
Chitine
Cildabrin
Darkmantle 1/2
Derro
Dire Corbie
Drow 1/4
Drow elite warrior 5
Fungus, violet 1/4
Gargoyle 2
Ghast 2
Ghoul 1
Gibberling
Gibberling, brood
Grick 2
Hell hound 3
Howler
Ibrandulin
Lith
Meazel
Minotaur 3
Phaerlock
Quaggoth 2
Roper 5
Rothe, deep
Shadow 1/2
Spawn of Kyuss
Spider, giant 1
Spider, giant wolf 1/4
Swarm of bats 1/4
Troglodyte 1/4
Troll 5
Umber hulk 5
Vampire spawn 5
Vargouille
Vermin lord
Wererat 2
Wight 3
Wraith 5
Wyste
Xorn 5
Zombie 1/4[/SBLOCK]

[SBLOCK=Monsters, Frontier]
Abishai, black
Baphotaur
Bat, giant 1/4
Baneguard
Beholder, gauth
Bodak
Bugbear 1
Bugbear chief 3
Chitine, hunters
Cildabrin
Cloaker 8
Cockroach, giant
Desmodu
Dire corbie
Dragon, young copper 7
Dragon, young black 7
Dragon, young deep
Dragon, young red 10
Dragonkin
Drow 1/4
Drow elite warrior 5
Duergar 1
Earth Glider
Ettin 4
Foulwing
Ghaunadan
Giant, phaerlin
Giant, stone 7
Gloura
Goblin 1/4
Goblin boss 1
Grick 2
Grimlock 1/4
Gray render
Hound of the gloom
Lamia 4
Lurker
Lurking strangler
Medusa 6
Metalmaster
Mind flayer 7
Mindshredder larva
Mohrg
Nifern
Nycter
Ooze, black pudding 4
Otyugh 5
Phaerlock
Psurlon, average
Raggamoffyn, shrapnyl
Reason stealer
Roper 5
Roper, prismatic (near the Deep Reach)
Scaladar (near Undermountain)
Scorpion, giant 3
Skindancer
Slaad, red 5
Spellgaunt
Spider, harpoon
Spider, giant 1
Spider, giant sun
Spider, giant whip
Spider, shadow
Spider, subterranean (sword)
Stonesinger
Susurrus
Svirfneblin 1/2
Swarm of bats 1/4
Swarm, swamp strider
Troglodyte 1/4
Troll 5
Umber hulk 5
Vampire spawn 5
Wererat 2
Wraith 5
Xorn 5[/SBLOCK]

 

[Prism]

I have been using the 5e DMG guidelines with some success. Encounter chance 18-20 on a D20, rolled x times per day. I tend to go for 3-4 times per day. You can also apply a modifier to the encounter chance to represent more populated areas. So remote unpopulated areas might get -2 to the roll making it 1 in 20 whereas others might get +2 making it 1 in 4. I also allow survival checks to reduce the chance if the party wishes

 

[Corpsetaker]

1: Drow Patrol.
2: Hook Horror.
3: Duergar.
4: Displacer Beast.
5: Grimlocks.
6: Quaggoths.

 

[Hand of Evil]

Don't make just one encounter table, make three or four based on the depth in the underdark you are.

• The first level / table would have a lot of creatures you may see on the surface world, they are your raiders and go between. You will find caravans, ruins, mines, dungeons, etc in this level. Encounters should reflect that.
• The second would be the level the drow live on and creature that would be rarely seen on the surface, hunters in the dark. You would find cities here, patrols, wilderness areas, ruins, areas of conflict.
• The third table would be the deeps, things even the drow are wary of.

 

[Wik]

I've been using wandering monster tables a lot in my 5th campaign. What I've come to realize, is that while it might be cool to have very specific type encounters, you're better off having your table be such that you can roll the same encounter multiple times, and not necessarily have your players realize it.

So, no named monsters. Keep monster patrols based around random(ish) numbers. And be ready to modify things as needed.

Also, a great way to do a table is to have an option on every one of them to roll two encounters. Something like this:

96-00. Roll on the monster table twice, ignoring further results of 96-00. Both encounters appear. Roll a d4. On a 1, the monsters are engaged in combat when the PCs arrive. On a 2, they are allied together in an unlikely alliance. On a 3, they are engaged in a standoff, and their argument might change on the PCs' arrival. On a 4, they are engaged in some form of friendly or neutral exchange.

I also like having some "what the hell?" encounters on every table. In the spelgard 4e wandering monster table, there's a 1% chance that the PCs will actually encounter the ghost they're going through the entire adventure to contact. Naturally, my players did just that. It derailed the entire adventure, but in a very good way. Highly recommend this sort of encounter - it'll keep you on your feet.

Obviously, monster patrols are great. Try to mix em up if you can - they feel less "wandering monster-y" if your encounters contain multiple statblocks. So, Drow with Quaggoths and a lieutanent mage, or Kuo-Toa with a captured ogre, or Mind Flayers with an Umber Hulk. Just make sure you have a rough idea of treasure they'll be carrying.

You've already mentioned it, but tables should have "weather effects". Underground, these would be cave-ins, stalactites falling, fungal hazards, unusual winds, floods, etc.

Finally, social encounters are great because they break my prior rule about non-specific monsters. It's wonderful when the players continually bump into the same merchant. Seriously, throw a named NPC on every table. And I highly recommend seeding a table with merchants, so PCs can sell excess loot. Just remember that the merchant takes a high percentage, and you're set!

 

[ccooke]

For what it's worth... I used the allip as one of my tests of the DMG monster creation rules a while back. I'm quite happy with the result - it worked out about right for CR3 when I ran it:

[sblock=Allip]
Medium undead, evil
---------------------------------------------
Armour Class 13
Hit Points: 24 (6d8)
Speed 0ft, fly 40ft
---------------------------------------------
STR 7, DEX 12, CON 10, INT 11, WIS 11, CHA 18
---------------------------------------------
Damage Resistances: acid, fire, lightning, thunder, bludgeoning, piercing and slashing from nonmagical weapons
Damage Immunities: cold, necrotic, poison
Condition Immunities: charmed, exhaustion, frightened, grappled, paralyzed, petrified, poisoned, prone, restrained
Senses: Darkvision 60 ft, passive Perception 11
Languages: The allip cannot speak intelligably, but understands any languages it knew in life
Challenge: 3 (700xp)
---------------------------------------------
Ethereal Sight: The allip can see 60 feet into the Ethereal Plane when it is on the Material Plane and vice versa

Incorporeal Movement: The allip can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inide an object

Gibbering: The allip babbles incoherently while it can see any creature and isn't incapacitated. Each creature that starts its turn within 20 feet of the allip and can hear the gibbering must succeed on a DC 15 Wisdom saving throw. On a failure, the creature can't take reactions until the start of its next turn and rolls a d8 to determine what it dows during its turn. On a 1-4, the creature does nothing. On a 5 or 6, the creature takes no action or bonus action and uses all its movement to move in a randomly determined direction. On a 7 or 8, the creature makes a melee attack against a randomly determined creaure within its reach or does nothing if it can't make such an attack.

Madness: Anyone targeting an allip with a thought detection, mind control, or telepathic ability makes direct contact with its tortured mind. Its Wisdom is reduced by 1d4.
---------------------------------------------
Actions

Touch of Madness. The allip attempts to touch one creature within 5'. The target must succeed on a DC 15 Dexterity saving throw or its Wisdom is reduced by 1d4 and the allip regains 5hp. If this reduces the target's Wisdom to 0, the target is stunned until it regains at least one point of Wisdom. Otherwise, the reduction lasts until the target takes a short or long rest (The target cannot take a long or short rest while on 0 Wisdom)

Etherealness. The allip enters the Etheral Plane from the Material Plane or vice versa. It is visible on the Material Plane while it is in the Border Ethereal and vice versa, yet it can't affect or be affected by anything on the other plane.
---------------------------------------------
[/sblock]

Dropping it in here in case it's useful to you (or anyone else, I guess)

 

[Rhenny]

When I ran my last underdark adventures, I made a table that mixed interesting exploration and obstacle encounters with creature encounters. It really helped the flow (sandbox/improv) of the games. For instance, one encounter was a set of spears stuck in the ground with a large feline skull atop the spears. This gave the party something to think about and it linked well with other encounters: a displacer beast ambush, an encounter with some lizardman sentries, and a longer more interesting encounter with the lizardman tribe and its chief. The spear encounter, the displacer beast and the lizardman sentries were random, but they grew the story to give the party a chance to interact with the tribe and lizardman chief. It was great fun.

Other encounters included sheer cliffs that the party had to scale in order to continue on their path, a ruined gazebo with strige hiding in it, a 40' pool they had to traverse (with an albino crocodile that grabbed one of the swimmers and tried to drag him down - very exciting).

 

[Mercurius]

The thought that came to mind is why not make a spreadsheet with every single possible monster in the first column, then do individual columns for different regions, with numbers in them if and when a specific monster could be encountered within a specific region. That way you can make an encounter table rather quickly - just create a new column for the session, each customized for the region where the PCs are moving through. Eventually you'll have a handy spreadsheet with many regions and encounter tables.

 

[Quickleaf]

Finally, social encounters are great because they break my prior rule about non-specific monsters. It's wonderful when the players continually bump into the same merchant. Seriously, throw a named NPC on every table. And I highly recommend seeding a table with merchants, so PCs can sell excess loot. Just remember that the merchant takes a high percentage, and you're set!

I'm considering using a random reaction roll for intelligent monsters, borrowed from here. 2d6, 2-5 hostile, 6-8 indifferent/wary, 9-12 neutral/friendly/open to trade. And double values (e.g. snake eyes) have special meanings:

[SBLOCK=Double Values]
1's. The monster takes hostile or violent action because of an outside influence. Perhaps the monster is charmed, acting under compulsion from another creature that is holding its young hostage, etc.
2's. Something happened recently to make the monster angry and hostile to the world in general. Negotiation is unlikely to succeed unless it resolves the cause of this underlying anger.
3's. The monster would prefer to be aggressive toward the party, but something holds it in check. Perhaps it is acting under orders, has taken a vow, or is favorably disposed to one aspect of the PCs’ appearance despite hating the rest.
4's. The monster would be favorably inclined to the party except for one nagging detail. Perhaps it is prejudiced against one particular party member, or upset about a past action of the PCs.
5's. Something happened recently to make the monster happy and well-disposed to everyone it meets. Negotiation is likely to succeed unless the PCs seem inclined to take away the thing that is making the monster happy (a pile of treasure, a tasty human baby).
6's. The monster receives the party enthusiastically due to mistaken identity or a belief that they fulfill a prophesy. All will go well as long as the PCs continue to conform to the monster’s expectations.[/SBLOCK]

So if I roll "2d4 kuo-toa, neutral/friendly/open to trade" is that what you mean by a specifically social encounter? Or do you mean an entry that says, for example, "Lipoloop: unhinged kuo-toa spell component trader"?

 

[Wik]

So if I roll "2d4 kuo-toa, neutral/friendly/open to trade" is that what you mean by a specifically social encounter? Or do you mean an entry that says, for example, "Lipoloop: unhinged kuo-toa spell component trader"?

The latter. Specific NPCs that the characters can interact with throughout the campaign. It's always worked well with me... in my Dark Sun merchant game, a lot of rolls of "merchant" tended to lead to the same three or four specific merchants. Good times.