TEXT:  
   
   
   
   
   
   
   
   
   
   
   
   
   
  by Ruslan Kim 
   
   
   
   
   
  DUNGEONS & DRAGONS, D&D, Wizards of the Coast, Forgotten Realms, Ravenloft, Eberron, the dragon ampersand, Ravnica and all other Wizards 
  of the Coast product names, and their respective logos are trademarks of Wizards of the Coast in the USA and other countries. This work contains 
  material that is copyright Wizards of the Coast and/or other authors. Such material is used with permission under the Community Content Agreement 
  for Dungeon Masters Guild. All other original material in this work is copyright 2019 by Ruslan Kim and published under the Community Content 
  Agreement for Dungeon Masters Guild. 
  
   
  About this Guide 
  Combat is one of three main pillars of the game, 
  apart from exploration and interaction. And it 
  takes a lot of time to prepare and run good 
  combat encounter. The goal of this guide is to 
  help DMs who are running Waterdeep: Dungeon 
  of the Mad Mage adventure to get better 
  understanding on how to run combat encounters, 
  how to make them coherent, memorable and fun! 
   
  Preparation process divided into 3 steps: 
  1. Determining Encounter Difficulty. 
  2. Determining Surprise. 
  3. Determining Creatures’ Tactics. 
   
  First step will give you general understanding 
  about how difficult combat encounter might be 
  for your player characters. Each level of WDMM is 
  designed for PCs of particular level. I use a 
  guideline from Encounter Building section in 
  Xanathar’s Guide to Everything (XGE, p. 88) to 
  evaluate how many PCs of corresponding level 
  should be in the party to overcome the encounter. 
  Math is simple. If you have the same number of 
  PCs – it is good fight. If you have more PCs (2/3 of 
  number of PCs is needed) – they will pass it with 
  ease, but it still be challenging. If you have less 
  PCs (3/2 of number of PCs is needed) – encounter 
  will be hard, but still winnable. Also, I put notes 
  about combat difficulty, which I think is 
  important. Depending on this information you 
  can adjust the encounter for your group, skip it 
  entirely or think about possible defeat 
  consequences. 
   
  Second step is always up to DM, so you should be 
  prepared in advance. General guidance is written 
  in Player’s Handbook (PHB, p. 189). Basically, you 
  should determine who is surprised when the first 
  round of combat begins. To do so, you should 
  know answers for these questions: 
  Are creatures trying to hide? They roll Stealth. 
  Are they successful? Compare results to PC’s 
  Passive Perception score. 
  Are PCs trying to hide? They roll Stealth.  
  Are they successful? Compare results to 
  creatures’ Passive Perception score. 
  Based on the results you will understand who 
  will take actions in the first round of combat and 
  who will not. I also put my notes for the 
  encounters when circumstances may differ from 
  the standard procedure. 
   
  Third step will help you to understand how to use 
  creatures in combat. Where should they stand? 
  What course of action will be most efficient and 
  logical depending on the lore? Who do they need 
  to attack? Will they fight to the death? Will they 
  flee or surrender? I also put more detailed 
  explanation on how some creature’s abilities and 
  traits work. 
   
  Abbreviations and Font Styles 
  The following abbreviations are used throughout this 
  guide: 
  PHB = Player’s Handbook 
  MM = Monster Manual 
  DMG = Dungeon Master’s Guide 
  SCAG = Sword Coast Adventurer’s Guide 
  XGE = Xanathar’s Guide to Everything 
  VGTM = Volo’s Guide to Monsters 
  MTOF = Mordenkainen’s Tome of Foes 
  WDMM = Waterdeep: Dungeon of the Mad Mage 
  WDH = Waterdeep: Dragon Heist 
  PC(s) = Player Character(s) 
  AC = Armor Class 
  DC = Difficulty Class 
  CR = Challenge Rating 
  hp = hit points 
  gp = gold piece(s) 
  AoE = Area of Effect 
  RAW = Rules as Written 
   
  The following font styles are used throughout this 
  guide: 
  Bold style is used for the creatures’ names 
  Italic style is used for the Spells. 
  Bold Italic style is used for the Abilities and Traits. 
  
   
  Level 17: Seadeeps 
  This level is designed for four 14th level PCs. If 
  you have more than 4 PCs, you can add more 
  creatures or maximize their hp to make combat 
  encounters more challenging. If you have less 
  PCs, you can decrease the number of creatures in 
  combat or use less optimal tactics. All creatures 
  in Encounter Difficulty section are compared to 
  14th level PCs. 
   
  Area 4 
  Encounter Difficulty 
  9 Flumphs (CR 1/8, MM, p. 135) = 1 PC 
  Note. These creatures fight only in self-
  defense. This is very easy encounter for 14th level 
  party, so you can skip it. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. Thanks to Advanced Telepathy the 
  Flumphs can’t be surprised by creatures with 
  any kind of Telepathy. 
   
  Creatures’ Tactics 
  Flumphs are mysterious Underdark creatures 
  which feed by siphoning mental energy from 
  psionic creatures. They aren’t evil and can 
  communicate, flee, surrender or take captives. 
   
  The Flumph can fly so make it stay in the air out 
  of melee reach between its turns. Make the 
  Flumph use Stench Spray targeting as many PCs 
  as possible. After that use Tendrils against less 
  armored PC. 
   
  Area 6a 
  Encounter Difficulty 
  4 Githyanki Warriors (CR 3, MM, p. 158) = 2 PCs 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
  Creatures’ Tactics 
  Githyanki are a psionically gifted race of 
  conquerors and raiders living in timeless Astral 
  Sea (PHB, p. 300). They are intelligent creatures, 
  so they can communicate in Gith language, flee, 
  surrender or take captives. They hate mind 
  flayers and githzerai, so you can make the 
  githyanki focus on them if any are in the party. 
   
  Make the Githyanki Warriors use Multiattack 
  against less armored PC. You can make them cast 
  Misty Step as Bonus action to reach the target or 
  avoid opportunity attacks. 
   
  Area 7a 
  Encounter Difficulty 
  4 Githyanki Warriors (CR 3, MM, p. 158) = 2 PCs 
  Note. Fight in this area alerts creatures from 
  Area 7b and Area 7c. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  See Area 6a. 
   
  Area 7b 
  Encounter Difficulty 
  4 Githyanki Warriors (CR 3, MM, p. 158) = 2 PCs 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  See Area 6a. 
   
  
   
  Area 7c 
  Encounter Difficulty 
  2 Githyanki Knights (CR 8, MM, p. 158) = 4 PCs 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  Make the Githyanki Knight cast Telekinesis 
  targeting less armored PC to grant Advantage to 
  its allies’ attacks against him or her. Gith racial 
  spells don’t require any components which 
  makes them impossible to Counterspell. Once 
  Telekinesis is ended or not needed, make the 
  Githyanki Knight use Multiattack against less 
  armored or Restrained PC casting Misty Step if 
  needed before or after. 
   
  Area 8a 
  Encounter Difficulty 
  1 Neothelid (CR 13, WDMM, p. 315) = 5 PCs 
  Note. The Ulitharid from Area 12g can’t sense 
  the Neothelid, because it has less than 4 
  Intelligence. In cas the Ulitharid can sense PCs it 
  can send reinforcements here anytime you want. 
   
  Surprise 
  PCs without Mind Blank or Nondetection spells 
  cast on them can’t surprise the Neothelid 
  because of its Creature Sense trait. Follow the 
  standard procedure to determine if it can 
  surprise PCs. 
   
  Creatures’ Tactics 
  Neothelids are fearful abominations driven by 
  hunger for creatures’ brain. It can’t communicate, 
  flee, surrender, take captives of use advanced 
  tactics. 
   
  Make the Neothelid cast Confusion targeting as 
  many PCs as possible. Note, that its spells require 
  no components, so PCs won’t be able to cast 
  Counterspell. Next round make the Neothelid cast 
  Feeblemind targeting nearest PC with lesser 
  Intelligence score within range. Thanks to 
  Creature Sense trait the Neothelid knows each 
  creature’s Intelligence score. Next rounds make 
  the Neothelid use Acid Breath if it can target 2 
  or more PCs. Otherwise, make it use Tentacles 
  against nearest PC. 
   
  Area 9 
  Encounter Difficulty 
  2 Mind Flayers (CR 7, MM, p. 221) = 4 PCs 
  8 Orogs (CR 2, MM, p. 244) = 2 PCs 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  Mind flayers are psionic tyrants and slavers who 
  devour brains of intelligent creatures. They can 
  negotiate, flee, surrender or take captives. 
   
  The Mind Flayers can cast Levitate before the 
  combat to stay out of melee reach. Mind Blast is a 
  good start, because it damages and disables PCs 
  within good AoE. On the next round make the 
  Mind Flayer cast Dominate Monster, but don’t 
  forget that this will break Concentration on 
  Levitate. The Mind Flayer is smart enough to use 
  this spell against martial PC, rather than 
  spellcaster. If Mind Blast is not available, the 
  Mind Flayer can attack in melee focusing on less 
  armored or Stunned PC. Tentacles and Extract 
  Brain attacks work in conjunction. Successful 
  Tentacles attack inflicts Grappled condition 
  automatically and if PC fails saving throw it also 
  inflicts Stunned condition. Stunned condition 
  includes Incapacitated condition which allows the 
  Mind Flayer use Extract Brain on the next 
  round.  
   
  
   
  Orogs are orcs blessed with a surprisingly keen 
  intellect that ordinary orcs believe is a gift from 
  the orc goddess Luthic. These orogs are thralls 
  under the illithids’ command and defend their 
  alien masters to the death. According to VGTM 
  (See VGTM, p. 75), a thrall can be restored to its 
  former self through a combination of spells and 
  ministration. The thrall must have Regenerate, 
  Heal and Greater Restoration cast on it once per 
  day for three consecutive days. The victim is 
  restored to normal when the final round of spells 
  is cast. 
   
  Make the Orogs use Multiattack against less 
  armored or Stunned PC. The Orog can use 
  Aggressive trait as Bonus Action to reach its 
  target when needed. Make the Orog use Javelin 
  only if there is no chance to attack in melee. 
   
  Area 10 
  Encounter Difficulty 
  1 Intellect Devourer (CR 2, MM, p. 167) = 1 PC 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can send reinforcements here. 
   
  Surprise 
  It is impossible for PCs to surprise the Intellect 
  Devourer because of its Detect Sentience trait. 
  Follow the standard procedure to determine if it 
  can surprise PCs. As a DM you can make party 
  surprised when the Intellect Devourer willingly 
  leaves its host. 
   
  Creatures’ Tactics 
  There is not so much information about intellect 
  devourer’s behavior from the lore point of view. 
  Apart of Monster Manual, you can find some 
  additional information about this creature in 
  published books (WDH, p. 212 and VGTM, p. 77) 
  but there are no clues on how it behaves. Intellect 
  devourers have alien intelligence, but they can 
  communicate using Telepathy, so it is up to DM if 
  they will negotiate, flee, surrender or take 
  captives. 
   
  While inside the Grimlock, the Intellect 
  Devourer can’t use its own attacks. It can leave 
  the Grimlock anytime and it teleports outside 
  once the host is dead. Intellect Devourer’s 
  Multiattack includes Devour Intellect action. 
  Devour Intellect can inflict Stunned condition 
  (PHB, p. 292), which can be ended by Greater 
  Restoration spell. Stunned condition includes 
  Incapacitated condition and allows the Intellect 
  Devourer to use Body Theft next round. If PC 
  dies because of Body Thief ability, Revivify and 
  even Raise Dead spells will not work, since they 
  don’t restore any missing body parts. The easiest 
  way to bring PC back to life is Resurrection spell. 
   
  Area 12f 
  Encounter Difficulty 
  2 Mind Flayers (CR 7, MM, p. 221) = 4 PCs 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  See Area 9. 
   
  Area 12g 
  Encounter Difficulty 
  1 Ulitharid (CR 9, WDMM, p. 316) = 3 PCs 
   
  Surprise 
  PCs without Mind Blank or Nondetection spells 
  cast on them can’t surprise the Ulitharid because 
  of its Creature Sense trait. Follow the standard 
  procedure to determine if it can surprise PCs. 
   
  
   
  Creatures’ Tactics 
  Ulitharid is a larger and more potent mind flayer 
  that boasts six tentacles. It has almost genius 
  level of intelligence and can negotiate, flee, 
  surrender or take captives. 
   
  The Ulitharid has Project Image spell. It’s not 
  combat spell, but you can use it to communicate 
  with PCs if you need to once they arrive on this 
  level. Make the Ulitharid always have Levitate 
  spell casted on it, so it will be able to stay out of 
  melee reach if combat occurs. Mind Blast is the 
  best attack the Ulitharid has, because it damages 
  and disables PCs within good AoE at once, so use 
  it every time it’s available. On the next round, if 
  Mind Blast didn’t recharge, make the Ulitharid 
  cast Confusion targeting as many PCs as possible, 
  but don’t forget that this will break Concentration 
  on Levitate. Next round it doesn’t have Mind 
  Blast and Concentration on Confusion is broken 
  or not needed, make the Ulitharid cast Dominate 
  Monster on martial non-elf PC. As an alternative 
  you can make the Ulitharid cast Feeblemind on 
  spellcaster with low Intelligence score. Thanks to 
  Creature Sense trait the Ulitharid knows each 
  creature’s Intelligence score. While it’s not very 
  good idea, the Ulitharid can fight in melee 
  focusing on less armored or Stunned PC. 
  Tentacles and Extract Brain attacks work in 
  conjunction. Successful Tentacles attack inflicts 
  Grappled condition automatically and if PC fails 
  saving throw it also inflicts Stunned condition. 
  Stunned condition includes Incapacitated 
  condition which allows the Ulitharid use Extract 
  Brain on the next round. Instead of fighting to the 
  death the Ulitharid can cast Mass Suggestion and 
  try to suggest PCs reasonable way to end violence 
  or it can simply try to run away. 
   
  Area 12h 
  Encounter Difficulty 
  4 Ettins (CR 4, MM, p. 167) = 3 PCs 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
  Surprise 
  Follow the standard procedure to determine 
  surprise. Note that Two Heads trait gives +5 to 
  the Ettin’s Passive Perception score (see Passive 
  Checks, PHB, p. 175). 
   
  Creatures’ Tactics 
  Orcs transformed by magic of Demogorgon 
  became the first ettins. These ettins have had 
  their minds broken by the mind flayers and fight 
  to the death. According to VGTM (See VGTM, p. 
  75), a thrall can be restored to its former self 
  through a combination of spells and ministration. 
  The thrall must have Regenerate, Heal and 
  Greater Restoration cast on it once per day for 
  three consecutive days. The victim is restored to 
  normal when the final round of spells is cast. 
   
  Make Ettins use Multiattack against nearest PC. 
   
  Area 14 
  Encounter Difficulty 
  4 Mind Flayers (CR 7, MM, p. 221) = 8 PCs 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  See Area 9. 
   
  Area 15 
  Encounter Difficulty 
  3 Mind Flayers (CR 7, MM, p. 221) = 6 PCs 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
  
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  See Area 9. 
   
  Area 16a 
  Encounter Difficulty 
  2 Scaladar (CR 9, MM, p. 86) = 6 PCs 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  These constructs have duergar’s brains 
  implanted. They understand Dwarvish and 
  Undercommon, which means they can 
  communicate with creatures with Telepathy or 
  similar abilities. It’s up to DM if they can flee, 
  surrender or take captives. 
   
  Make the Scaladar use Multiattack against less 
  armored PC. 
   
  Area 16b 
  Encounter Difficulty 
  8 Duergar (CR 8, MM, p. 158) = 1 PC 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
  Creatures’ Tactics 
  Duergar are greedy race of Underdark slavers. 
  These duergar have had their minds broken by 
  the mind flayers and fight to the death. According 
  to VGTM (See VGTM, p. 75), a thrall can be 
  restored to its former self through a combination 
  of spells and ministration. The thrall must have 
  Regenerate, Heal and Greater Restoration cast on 
  it once per day for three consecutive days. The 
  victim is restored to normal when the final round 
  of spells is cast. 
   
  If there is a chance make the Duergar use 
  Enlarge and Invisibility before the fight. 
  Otherwise, make the Duergar use Enlarge at the 
  beginning of the fight and use Warpick against 
  less-armored PC next turn. Use Javelin only if 
  there is no chance to use Warpick. 
   
  Area 16c 
  Encounter Difficulty 
  2 Mind Flayers (CR 7, MM, p. 221) = 4 PCs 
  Note. The Ulitharid from Area 12g is able to 
  sense all creatures with Intelligence score 4 or 
  higher within 2 miles and communicate with 
  them, so it can warn these creatures and send 
  reinforcements anytime you want. 
   
  Surprise 
  Follow the standard procedure to determine 
  surprise. 
   
  Creatures’ Tactics 
  See Area 9. 
  
SOURCE: textdata/thevault/Dungeons & Dragons [multi]/MGtCE of DotMM 1-23/Monsters' Guide to Combat Encounters - For Dungeon of the Mad Mage Level 17 - Seadeeps.pdf