Corpse Chewer - Or a semi-improv, low prep 13th Age One shot you could run too

After the election my wife asked me to run a combat heavy one shot RPG as a distraction, I've been burnt out a little on 5e D&D lately, so I decided to run 13th Age instead.

I like 13th Age for this kind of adventure/monster fighting combat heavy game because...

• It's basically D&D. I mean, it's not official Wizards of the Coast branded D&D(TM) but it's got a unified d20 mechanic like recent D&D, the classic classes, races and a lot of the feel.
• It's good at what it does and focuses on that. It's not the game I'd run if I wanted to run a social intrigue game (probably, right now, V20 Vampire the Dark Ages would win) or the game I'd run if I wanted a gritty game where the PCs struggled to survive (for now, that would probably be Shadow of the Demon Lord) but for a combat heavy game where PCs will have cool stuff to do during combat and you want a high fantasy feel it's an excellent choice. 
• 13th Age PCs are surprisingly simple(ish). For the game I just used some pre-made 4th level characters (and recommend you do too) and they all fit onto a single page without needing a magnifying glass to read the type. Even if players make their own PCs, they really only need their class write up at hand to play and won't need to flip between multiple sections of the core book the way any of the spellcasting classes in 5e D&D do (and remember that 5 of the 12 classes of 5e have spellcasting and gain or can gain spells, though that Totem Barbarian who gets two spells as rituals won't need the book as much as the wizard, but still...)
• Icon Relationships, Backgrounds and One Unique Things encourage player investment, even for one shot characters.
• A few memorable one unique things from when I ran this...
• Renowned as a 'fuck-up'.
• Attracts random cats when she sings.
• Half of his face looks like a corpse.

So, without further ado, here is Corpse Chewer, a semi-improv, low prep 13th Age One shot. It's semi-improv because I'm providing the skeletal sketch of the plot arc and combat encounters but you can improvise the description of the dungeon and environs itself and some of the flavor bits can be tailored to the icon relationships the players pick.

The Pitch: The PCs all have negative icon relationships with the Lich King, they're sent to an isolated cemetery where they're told a living dungeon called "Corpse Chewer" is about to surface and told to get their hands on magical staff the Lich King lost long ago before anyone else.

The PCs: As I said above, I recommend using the set of pre-made 4th level PCs, and I made a sheet for each guiding the player through choosing Icon Relationships, Backgrounds and a One Unique Thing that you can grab here. If you're letting players make their own PCs, or making your own for them then they should.

• All (or most, maybe?) should have a negative relationship with the Lich King.
• They should be 4th level.
• That's it. If you're popping this into a campaign then maybe be a little stingier with loot, but that's your call as GM.

For the purposes of the rest of this adventure write up, I'm assuming you're running this as a one shot, just FYI.

Prep Work for before the Game: Provide players the PC sheets to choose from, read over and familiarize yourself with the sheets of any PCs that are chosen so that you understand their mechanics and can answer player questions. Likewise, read over the monsters and select any alternates if you don't have the 13th Age Bestiary or 13 True Ways book. Plan that the adventure will take 4-5 hours. It took me a little under 5 hours with 7 players and some time was spent finishing characters and ordering pizza.

Starting: Help the players chose Icons, Backgrounds and One Unique Things, then have them introduce their characters to the rest of the table. Pick the heroic Icon that has the most PCs tied to it (in my game it was the High Druid), tell the players who have a relationship to that Icon that they are in charge of the party and are officially its leaders. Tell the players the pitch above, embellishing as you want. If the PCs would know stuff based on their One Unique Thing or a background toss that in too. When I ran, I decided the cemetery was near Concord, but it can really be anywhere (but I recommend someplace warm-ish). I forgot to give the cemetery a name, but perhaps the name has been long forgotten or you've got something good in mind. Corpse Chewer is a living dungeon, so the players should know that it burrows through the underworld, emerging now and then to swallow up a chunk of a cemetery to add to or repair itself. The powerful staff is said to be at the heart of Corpse Chewer, so the players should understand they need to get to the heart of the dungeon.

Roll Icon Dice: Have the players roll Icon Dice like normal and then give loot for 5's and 6's. For starting 5's I let that player choose two one use items (potion, oil or rune) for their PC and for 6's I chose a magic item to give them that seemed to fit that icon, letting me make sure the Forgeborn Paladin with a tie to the Dwarf King started the game with a magic golden beard.

Arriving at the Cemetery: You could have the players help with a montage, asking one player about a danger that the party encountered on the way to the cemetery and how their PC discovered it, then asking the next player in line how their PC was instrumental to the party overcoming it. Or you could just fast-forward to the group arriving, like I did. One of the players will probably try to scout ahead or otherwise try to get the lay of the land, they should learn the following.

• There is an orc encampment about a quarter mile from the cemetery. The orcs are flying a banner of a villainous icon that your PCs have a negative relationship to. In my game it was the Crusader. The PCs can easily avoid the encampment if they want.
• The cemetery walls are not 10-15ft tall in most places, but there is a central gate the PCs could enter through. Either way, the PCs won't have a hard time getting in.
• The weather is warm, but the cemetery walls are coated in frost and the PCs can see ice and frost inside. Any PCs that have ties to the Three should know that White Dragons seem themselves as enemies of the Lich King and often make their homes in cemeteries to fight his presence. Otherwise pick a PC that has a background that would explain why they know that fact and pass on the information so they know there is probably a white dragon in the cemetery.
• They should feel slight trembling in the ground as Corpse Chewer approaches the cemetery.

There is a huge white dragon (I named it Vatnajökull after the largest glacier in Iceland, but feel free to give it a different name if you want), it has realized that Corpse Chewer is on the way. It will confront the PCs when they enter the cemetery and its dramatically appropriate (I had it confront them when half the PCs had climbed over the fence and the other have was still outside). It has no beef with the PCs (unless they have a lot of negative relationships with the Three, and then maybe not even then) and will tell them it will trust them and let them into the cemetery and by extension Corpse Chewer, if they go wipe out the orc encampment for it. If they already did that, then the dragon should thank them and let them get to Corpse Chewer. If they're rude or attack first the dragon will defend itself.

Here is the dirty secret of my design here... I planned that the PCs would have a fight outside of Corpse Chewer, either with the dragon or with the orcs. Unless you have tons of extra time, I wouldn't run both. If the PCs wiped out the orcs and then wanted to rumble with the dragon too I'd have it fly off to deal with attaching hordes of undead sent by the Lich King and have the PCs realize that they need to get into Corpse Chewer ASAP. Don't be afraid to say something like "It's obvious that if you don't go in now you won't have another chance.

Battle One  - Option One: Orc Encampment. There are tents for a couple dozen orcs here. If the players are clever and would surprise attack and slay a bunch of orcs, just hand wave it and add those orcs to the encounter... For example, my players lit the tents on fire and so I just added a bunch of dead orcs to the combat so they felt like they had taken care of a bunch of enemies and kept my original encounter balance.

• Foes
• 1 Pit-Spawn Orc per PC (Bestiary pg. 156)
• Substitute Orc Packmate for them if you don't have the Bestiary
• 1 Death-Plague Orc per 2 PCs (Bestiary pg. 156)
• Substitute Dire Wolf if you don't have the Bestiary

Battle One - Option Two: White Dragon. If the PCs piss off the Dragon, it flies up and then breathes its icy breath down at them as it roars for its helpers and kobold archers emerge from their hiding spots amongst the tombs of the cemetery. When the PCs kill the dragon, any remaining kobolds flee.

• Foes
• 1 Huge White Dragon (Don't forget to give it 2 dragon abilities)
• 2 Kobold Archers per PC

Either way, after you finish the first battle, the players sshould roll icon relationship dice and you can give out loot, giving out single use items for 5's and true magic items that fit the icon for 6's. Don't forget to remind players they can use recoveries if they're unused to 13th Age.

Entering Corpse Chewer

After the first fight, let the PCs find Corpse Chewer as it emerges into the cemetery. I described the entrance as a gigantic skull made of thousands of human teeth that the PCs had to venture into the maw of but you can describe whatever you wish or have a player describe what they think the entrance to a living dungeon that devours cemeteries looks like. Have the players describe a marching order and establish who will be in front looking for traps. I find it works best to have one or two players who can make the roll to find traps instead of the whole table. 

First Skull Room

After a bit the PCs will come to a room full of skulls (or miscellaneous bones) and have the person in the front make a Wisdom check to find traps (DC 20), if they miss, then have a pit trap attack them. (+10 vs PD, 2d8 damage). Once the trap triggers or while they are disarming the trap (DC 20) have a Watch Skull attack (Bestiary pg 109) or substitute 3 Decrepit Skeletons or a Skeleton Archer emerging from the walls. The point is to give a trap and make the dungeon feel alive, like it's fighting back and to foreshadow the second skull room later, but the PCs should be able to quickly defeat the dangers here.

Dungeon Montage One

Pick a player, ask them about a danger their PC found in the dungeon. You can prompt them a bit if you want, asking something like "How did your PC discover the mummies that attacked?". Then after they have answered turn to the next player and ask them how their PC was instrumental to overcoming that danger. If this is the kind of thing your players enjoy, feel free to rinse and repeat. If it's not their jam, feel free to skip it.

Ghoul Chamber

Fair warning, I really like ghouls. To my mind, they're far superior to zombies. This is a warning because the ghouls from the 13th Age Bestiary are very ghoulish and lean on body horror, as you might guess from their names. If your players are squeamish, feel free to use the alternates. I described this chamber as a large round chamber filled with gore, with a corpse heap in the middle that was partially composed of ghouls. 

• Foes (add a non-mook ghoul of your choice per PC over 5 PCs in the party. If you don't have the bestiary, good substitutes for the non-mook ghouls would be Wights)
• 2 Newly Risen Ghouls per PC
• 1 Ghoul Pusbusters (Bestiary pg 97)
• 1 Ghoul Fleshripper (Bestiary pg 97)
• 1 Ghoul Licklash (Bestiary pg 97)

After the PCs defeat the ghouls the players should roll icon relationship dice and you can give out loot, giving out single use items for 5's and true magic items that fit the icon for 6's. When you're doing loot and such, if you used the Licklash, have the players roll Lich King icon rolls to see if any know about the special properties of the Licklash spit as described in the Bestiary 😜

Dungeon Montage Two

Second verse, same as the first, if you're into it.

Second Skull Room

However you decide to describe the first skull room, use that description again but make it bigger, like twice the size. After the first skull room the players should be wary, so let them find the foes easily. They'll be tempted to hang out in the hallway/corridor leading into this room, so after the first round have a second wave of foes attack from behind. If you're using demons instead of skulls because you don't have the bestiary, maybe say something about the eye sockets of the skulls in this room glowing with demonic energy?

• Foes
• 1 Slime Skull, or 2 if there are 6 or more PCs. (Bestiary pg 109)
• Substitute an Ochre Jelly for both Slime Skulls if you don't have the Bestiary and have it be the foe that attacks from behind.
• 1 Screaming Skull (Bestiary pg 110)
• Omit if you don't have the Bestiary
• 1 Flaming Skull (Bestiary pg 110)
• Substitute a Despoiler if you don't have the Bestiary.
• 1 Black Skull (Bestiary pg 110)
• Substitute a Despoiler Mage if you don't have the Bestiary.
• 1 Watch Skull per 3 PCs that attacks from behind after the first round (Bestiary pg 109)

If the players think to search this room, let them find a hidden chest with loot. Have them  roll icon relationship dice and you can give out loot, giving out single use items for 5's and true magic items that fit the icon for 6's.

Dungeon Montage Three

You know the drill by now, surely?

Corpse Chewer's Heart

For my game I described this as a massive cavern, containing a full graveyard/cemetery, with eerie black sunshine and dead withered trees. At the far end, was a mausoleum with a Skeleton standing up holding the staff flanked by two giant dandelions, the poison dandelions from 13 True Ways. Without that book, I'd substitute in Wraiths and replace the dandelions with sinister looking statuary. The skeleton holding the staff is just a skeleton and the staff is powerfully evil and it should be obvious to the players that they won't be able to use it effectively. If you have to, tell them that they think without careful study it would absorb their soul if they try to use it... it's here to be a macguffin, not an artifact the players can use.

• Foes
• 2 Poison Dandelions (13 True Ways pg 195). When they die, one turns into a Lich Flower (13 True Ways pg 194) and the other into a Death Blossom (13 True Ways pg 194)
• Substitute 4 Wraiths if you don't have 13 True Ways and have them have the Nastier Special.
• When the escalation die is odd, have 1d4 of the skeletal trees become Awakened Trees and attack (13 True Ways pg 202)
• Substitute 1d4+1 Newly Risen Ghouls climbing out of graves if you don't have 13 True Ways or maybe Dretchs if you went with the Demons and the PCs have ties to the Diabolist or Crusader.

Wrapping up

Once the PCs have killed the non-mooks in Corpse Chewer's Heart and have the staff, the living dungeon should start to collapse. Do another montage if you want asking players to describe how they get out or you could have them roll some checks to avoid falling debris and such or you can just hand-wave it and narrate it yourself.

And there you are, a fairly easy to prep one-shot that leaves plenty of room for the GM and players to twist it around a bit to suit their tastes. If you do run it, let me know how it went.