The adventure starts out in a prison at a drow outpost in the Underdark. But escaping their elven captors is merely the first trial that the adventurers must face. Demons now roam through the northern Underdark, spreading their madness as they go and twisting the land to suit their whims. Pursued by both the drow and hungry fiends, can the adventurers escape to the surface with their sanity intact?
This adventure provides examples of:
- A God Am I: Karazikar the Beholder considers itself a god, acts supremely arrogant, and has a slave named Shedrak of the Eyes that feeds into this perception. Since the players need a beholder's central eye in order to complete the summoning ritual, the most likely step is proving that Karazikar's belief in his own superiority is rather misplaced by making him part with that central eye.
- And I Must Scream: The Gallery of Angels, a small cavern of fallen angels who have all been turned to stone. The book spares no expense in detailing how dreadful their fate is.Even though they are transformed into stone statues, the fallen angels remain very much alive, their petrified bodies having become prisons for their minds and souls. They remember who they were. They know what they did and why they are here. They know everything transpiring around them. Yet they can do nothing. They are trapped forever, and the isolation, darkness, and endless torment of their fate have driven them mad. No spell can undo the angels' curse or free them from their petrified state.
- Arc Villain: How each of the Demon Lords is essentially handled prior to the finale. Each one appears in an area and acts as something of the overhead villain of that area, usually providing A Taste of Power to demonstrate why they are not to be messed with. This is because it would be impossible to get a real grasp on their power in the finale with how much chaos and fighters are present.
- Art Evolution: Most of the demon lords got their first 5e appearance in this book, and most of them have gotten minor artistic updates to make them look more demonic. Of note, the Demogorgon has lost a few baboon traits and gained Volcanic Veins.
- Because You Were Nice to Me: The minotaurs who guard the labyrinth employ a gnoll named Gash, whom they regularly abuse. If the party treats Gash nicely (or try to heal his wounds), he's genuinely confused at first, since no one's ever been nice to him. Should the party keep it up long enough, Gash will warn them about a trap that the minotaurs are planning to spring on them.
- Break the Haughty: Karazikar the Beholder believes itself to be a god. The party needs his central eye for part of Vizeran's ritual, and Karazikar isn't just going to give it up. Once the party gets him down to half-health or lower, Karazikar realizes he's not as strong as he thinks he is, tries to run, and leaves his favored slave Shedrak to die at the party's hands.
- Brought Down to Badass: The Final Boss is against one of the demon lords (probably Demogorgon, Prince of Demons) after he's already been weakened by battle against all of the other demon lords. While the demon lord has depleted health, fewer legendary actions, and penalties to his attacks, he is by no means an easy opponent.
- Dark Secret: Several of your fellow prisoners from the beginning have one of these, which might show up at any time during or after your escape. With the rising madness in the Underdark, several other characters might have at least one of their own as well.
- Demon Lords and Archdevils: As you might expect from the image, Demogorgon shows up at some point in the adventure. He's not the only one; a half-dozen other demon lords are loose in the Underdark, and even seeing one can be enough to drive a character to madness. And heavens help you if you decide to pick a fight with one...
- Dirty Coward:
- If the players get Karazikar the Beholder down to a low-enough HP threshold, it attempts to run away and leave his favored slave Shedrak to die at their hands.
- A nalfeshnee named Slaughtertusk guards the Maze Engine, though getting him weak enough will have him drop his weapons and beg for his own life. The text refers to him as The Bully, who can't handle being confronted with a legitimate challenge.
- Disc-One Nuke: There are four optional mini-dungeons that can be sprinkled throughout the first half of the adventure at the DM's discretion. One of them has a sentient sun blade named Dawnbringer that can be retrieved. Apart from the usual abilities of a sun blade, it can also cast Lesser Restoration once per day, which can cure short-term and long-term madness. In the right PC's hands, it'll buzzsaw through most any threat you encounter within the first half of the adventure, and it's still a great option all the way to the final boss battle. About the only downside is that it wants to stay on all the time, which will make you a beacon to the creatures of the darkness.
- Early Game Hell: The players, as prisoners of the drow, start the adventure with nothing more than the clothes on their backs and random trinkets scavenged during their incarceration. The gear they WOULD have started with is being kept in the bedroom of a priestess of Lolth, who can steamroll a level 1 party on her own (even with all ten of their fellow prisoners contributing). And even if they manage to escape their holding cell, grab their gear, and loot everything useful they can from the outpost, there's a strong chance that they might have their getaway interrupted by a demon attack (though this has its own advantages).
- Enemy Mine: A drow archmage named Vizeran DeVir enlists the help of the players in order to use a Summoning Ritual to stop the demon lords. He's listed as Lawful Evil, and while it's patently obvious that he's got something else going on and shouldn't be trusted, he at least won't stab the players in the back as long as they're helping him get what he wants.
- Final Boss: The final battle is intended to be one of the demon lords, and the book suggests that it's probably going to be Demogorgon, the Prince of Demons. The players are supposed to let the rest of the demon lords fight it out, then take out the last one while they're still weak.
- Final Boss Preview:
- Sloobludop, the village of the kuo-toa, is where Demogorgon first makes his appearance. While he causes some havoc, all the adventurers can do once they see Demogorgon is run. They get a chance to fight him for real at the end of the adventure once he's been weakened.
- Yeenoghu the Demon Lord wanders the Underdark after first being summoned, and the adventurers can run across him and his pack fighting against a goristro. A scripted encounter against the beast shows how powerful Yeenoghu is; Yeenoghu tears through the goristro — a monster with a Challenge Rating of 17 — with ease. The DM notes advise that fighting him now is suicide, and encourage the players to stay hidden at all costs.The characters' only advantage at this moment is that they haven't yet been detected. Considering their level at this stage of the adventure, the players might be creating new characters quite soon if they dare confront the demon lord.
- God Was My Copilot: One of the options for the final battle against the demon lords is that Jimjar, the deep gnome who was imprisoned along with the players, is a god in disguise. While he doesn't intervene, so as not to take away the chance for the players to triumph, he does offer a blessing to the party that tips the balance of the battle in their favor before vanishing.
- Great Big Library of Everything: To solve the problem of the demon infestation, the party ends up needing to return to the Underdark to visit one of these called Gravenhollow. There, the players can learn about how the demons were summoned in the first place, and what can be done to stop them. While there, everyone inside the library is always under the effects of the Comprehend Languages spell, to make finding and communicating whatever they need easier.
- Greater-Scope Villain: Not Demogorgon, though he's certainly no slouch in terms of sheer destruction. It's actually Lolth, who is taking advantage of the demon lords' absence to try and repopulate their layers of the Abyss with her own twisted spawn. An NPC can even remark that "chaos" is Lolth's goal.
- Great Escape: The first challenge player characters face is getting out of the jail that they're all trapped in to begin the adventure. And at level 1, fireballs and other high-powered magic tricks aren't yet available, so they need to get creative.
- Grey-and-Gray Morality: The situation with Themberchaud, the red dragon in Gracklstugh. He is a sapient creature unknowingly enslaved by a society that uses him as a living furnace to help them forge the city's weapons and armor. He is also unrepentant in his evil, and would not hesitate to slaughter the entire city or bring it under his heel, if he wasn't so indifferent towards the duergar as a whole.
- Heroic Sacrifice: Zigzagged. Vizeran DeVir suggests that the last thing needed for his ritual to stop the demon lords and seal them back in the Abyss is the life of an innocent person. He may or may not be telling the truth; it's hinted that this might be a Secret Test of Character to see how far the adventurers are willing to go to save the world. The implication from the text is that Vizeran is lying about needing the sacrifice, but the DM of a campaign has the option to make it be true if they want to see what the players will do.
- Let's You and Him Fight: Demons despise non-fiends, but they're not too fond of each other either, making this a possible tactic when they're encountered. This is also the ultimate plan to get rid of the demon lords and their minions; force them into the same area and let them kill each other off until one remains, then have the adventurers finish it off.
- The Jekyll Is a Jerk: Derendil explains that he's an elf prince cursed into the monstrous form of a Quaggoth, but the Quaggoth's vicious instincts are slipping out more and more. In fact, the Derendil persona is a demon-inflicted delusion, and if he's ever cured of his madness, he reverts to a violent brute forever.
- Miles Gloriosus: Karazikar the Beholder considers itself a god, acts supremely arrogant, and has a slave named Shedrak of the Eyes that feeds into this perception. However, the players need the beholder's central eye for a ritual to stop the demon lords, so they need to "convince" him to part with it. Should his HP get low enough, Karazikar will attempt to flee and leave his slave to die at the party's hands, as Karazikar has never faced an actual threat to his power before.
- Poke in the Third Eye:
- While in the library of Gravenhollow, characters can receive visions of things happening in the past, present, and future. One possibility with a scrying crystal is to scry Lolth, who is none too pleased with being watched. Thankfully, the magic of the ancient library prevents any damage from her retribution, though anyone who sees the vision needs to make a saving throw against gaining a level of madness.
- The Gallery of Angels features fallen angels who have all been turned to stone. Touching most of them will cause psychic damage and a few other effects, including gaining levels of madness or causing nightmares.
- Random Effect Spell: The effects from the Maze Engine are all over the place. They can range from really good (like a permanent +2 increase to any ability score) to really bad (like causing the adventurers to Time Travel all the way back to the beginning of the adventure to do it all over again).
- Revenge by Proxy: Vizeran DeVir wants this on Lolth, hence him teaming up with the adventurers. Unbeknownst to them, if the adventurers put the dark heart talisman in Menzoberranzan as planned, it will summon all of the demon lords there, causing them to flatten the city. Vizeran DeVir intends to use this to try and convince the drow that Lolth is not to be trusted and that they should abandon worship of her. The fact that this will kill several drow that annoy Vizeran DeVir is just icing on the cake.
- Sanity Ball: While the madness pervading the Underdark is making most characters overly paranoid, ravenous, or greedy, certain characters have been altered in such a way to make them less crazy.
- Shuushar, one of the characters imprisoned with the players at the beginning, is a kuo-toa that is incredibly calm and has become a pacifist, unlike the rest of his kind. As a denizen of the Underdark, he is also quite helpful in navigating the twisting tunnels and treacherous waterways, though useless in a fight.
- Stool the myconid is one of the few members of his kind to escape corruption from the Fetid Wedding between Juiblex and Zuggtmoy. This enables Stool to not only stay sane, but he can be very helpful by using his spores to give the equivalent of the Comprehend Languages spell.
- Sanity Meter: At several points, players must make saves to stave off madness. Depending on the inciting incident, they might end up with short-term, long-term, or indefinite madness, the latter of which can actually overwrite personality traits until they're cured. Demon lords have their own unique forms, some of which are caused just by looking at them.
- Schmuck Bait: The players can encounter Demogorgon as early as level 2 depending on their travel route. Nothing is stopping them from deciding to take him on (other than potential madness, of course), but the results of the Prince of Demons vs. a level 2 party are somewhat predictable.
- Shout-Out: The chapter 3 section "Slouching Toward Sloobludop" is likely an allusion to the Joan Didion essay "Slouching Towards Bethlehem" about the social fragmentation and upheavals in 1967 San Francisco. (And is itself a reference to the poem "The Second Coming" by William Butler Yeats)
- Spanner in the Works:
- Gromph Baenre, the archmage who tried to summon the demon lords in the first place, ends up getting a spanner thrown into his works by Lolth, the drow goddess. Gromph only wanted to summon one in an effort to bind the demon to his will. Vizeran DeVir calls that move a dumb enough decision by itself, but Lolth's interference summons all of the demon lords for the sake of causing more chaos. Gromph's fate is left ambiguous, though several NPCs in-universe can comment that, what with Gromph being so near to all of the Demon Lords at once, his chances of survival are not very high.
- The player characters can become this for Vizeran DeVir while preparing for his Dark Heart ritual, should they decide to place the finished Dark Heart somewhere other than Menzoberranzan. Doubly so if that place happens to be nearby his own wizard's tower, which, once the ritual is completed, would leave him in the epicenter of all the summoned demons and demon lords while he is dealing with three levels of exhaustion.
- Stern Chase: Early in the adventure, Ilvara and several drow will pursue the party, intending to recapture them at any possible opportunity. Depending on the choices the party makes, they may gain some lead time on their pursuers, or the drow might be breathing down the PC's necks by the time they reach a settlement to take refuge in. It eventually culminates in a showdown, which acts as the final obstacle to reaching the surface and the climax of part 1.
- Subterranean Sanity Failure: The PCs are stuck in the subterranean Death World of the Underdark at the same time as a demonic incursion spreads madness and (even more) monsters into its caverns. The module makes extensive use of a Sanity Meter — PCs could suffer short- or long-term madness from eerie encounters, pervasive magic, the stress of deprivation, or more, and will meet many insane NPCs along the way.
- Summoning Ritual: One of these cast by a powerful drow archmage, Gromph Baenre, is the cause of the demon lords and other demonic creatures being loose in the Underdark. Another drow archmage named Vizeran DeVir enlists the help of the player characters to perform a slightly altered ritual that will gather all the demons together and reduce their thought processes to mindless bloodlust so that they kill each other off. While this doesn't eliminate them permanently, it does put them back into the Abyss, leaving one last demon lord for the PC's to swoop in and finish themselves.
- Translator Buddy: Stool the myconid can serve as this. He's one of the NPCs in the cell at the beginning of the game, and ends up using his spores to give the equivalent of the Comprehend Languages spell to the party. This is quite useful to members who don't speak Undercommon, which is the most common language that they'll run into in the Underdark.
- Unholy Matrimony: Towards the end of the campaign, the Fetid Wedding will have the players trying to stop Zuggtmoy, Demon Queen of Fungi, from joining in an unholy union with Araumycos, the largest living creature in the Underdark (and quite possibly the entire world).
- What Happened to the Mouse?: Assuming the players are successful at stopping the demon lords, whatever happened to Gromph Baenre, the archmage who started this whole mess by trying to control a demon lord is never revealed. DM notes in the adventure say that it's best left to leave it open as a plot hook for another adventure.
- You All Meet in a Cell: The adventure begins with all of the player characters waking up in a cell as prisoners of the drow, along with multiple other NPC captives in the same room.
DISCLAIMER: Before you take on demon lords, consult a physician. Do not drink alcohol while taking on demon lords. Taking alcohol and demon lords may increase your risk of death. Other side effects may include hallucinations, mindless rage, gluttony, greed, paranoia, self-delusion, bestial urges, nihilism, hedonism, megalomania, a messiah complex, cannibalism, multiple personalities, and homicidal psychosis.
