Every DM has their own way of planning adventures. For myself, it involves a rough idea, and then research.
For the next session, the Thursday night group, known collectively as THE Group, plan to follow a map of sorts found in a 70-year-old journal. This map purportedly leads to an uninhabited dragon's lair, its treasures ripe for the plundering! Or they were, 70 years ago.
Still, something is there, or else the PCs would never have found the journal to begin with.
So now, the research begins.
I take what I already have: a sketchy map of the wilderness surrounding Ironguard Keep that I cooked up on Inkarnate and the journal-stated location, a fork in the River. There is also a wandering monster table (complete with Revenant hunting the PCs), but that is extra.
The map suggests this location is several hexes to the north, through the Troll Hills, forested foothills of the X Mountains. While I know they'll seek out the friendly werebear giant bee keeper for a meal and news, I don't yet know what other bits of interest THE Group will find.
So it is to the blog d4 Caltrops I go. Specifically the 100 hexes document there. I reckon there is bound to be something among the Forest and Mountain hexes.
Victory! The Predator Becomes Prey, particularly the White Hart option, because it is creepy and perfect for a land growing more and more twisted by Chaos. It has me thinking of something I read somewhere about carnivore deer spirits, so once I figure out where THOSE are, I'll be in good stead for an unHERD of encounter. (I found them! In Echoes from Fomalhaut #6 - a fun zine if you like your science fantasy with a heavy dose of weird).
Anyhow, The Tonsured Traveler looks promising, as does A Forgotten Graveyard - though this may be more useful alongside some proper Barrow Mounds. I'll try the mountain hexes before leaving the document to scour the site for the individual entries I know are there.
The Petrified Colossus might be turned to the Ozymandias reference I plan to work in, or the abandoned Iron Golem, so I'll pass for now. The Mountains prove a bust for what is in my head, so now to scour the d4 Caltrops blog for additional Forest hexes.
The Burbling Ford and the Moss Green Grotto look good, especially for nearer the River (because THE Group will most likely follow it north and west). Old Honey-Paws! I'll need to add some references to him to the rumor table, and maybe the beekeeper knows him. The Grandfather Tree, The Troll's Table, an Island in the Sky, and The Black Spring round things out to provide several options that the PCs may encounter. May being the operative word, because depending on how the evening goes, the PCs might miss some of them. The pain and pleasure of running a sandbox.
I'm tempted to use the Trail-Marker Tree, but my players will suspect it to be a portal or gate of some sort, and they wouldn't be wrong. So it will have to be saved for another day, perhaps when it becomes necessary to deal with the Seelie and/or Unseelie Courts. Time will tell.
Just reading through the options has my imagination in overdrive, but jamming everything together ruins it all. So A Hoard of Headstones can be saved for the Forgotten Graveyard and Barrow Mounds plan. The Wraithweald, as well. I'm confident if we get to play enough, THE Group will find these places and be amazed and or scared or both. So I'll add this paragraph to my 'loose ideas' document and follow through on it later.
With a rough idea of the journey ready, I'll lay out particulars in my notebook and shared docs, and play it out on a Thursday. Eventually, though, the PCs will reach the lair, and there had best be something worth the journey!
I already know the lair will be flooded to varying degrees, with much of the wyrm's horde lost to time, water, and other looters. Still, some treasures remain. If nothing else, a Coin Golem lies in a watery cave, shining in the PCs' torchlight. I'm not yet sure what a Coin Golem is, but it seems like good fun, maybe with a transmuting touch or spitting coins as missiles. All I know for sure is that there will not be a sentient sword present, as THE Group already have one that they are growing to dislike (and cannot even properly use, because alignment matters in this campaign).
For the record, the PCs that currently make up THE Group are 4th level across the board, (a Cleric, a Warlock, a Sorcerer, and a Barbarian, with assorted NPCs adventuring with them) and they already know the wyrm that laired here is long dead and reduced to a massive skeleton sheltering a cave (technically, the cave houses the Pod Caverns of the Sinister Shroom, but the players may not know that).
The PCs' level is somewhat important, because it suggests what makes for a good encounter - challenging, but neither too difficult nor too simple. Being incredibly lazy, I'll just pick some thematically fitting creatures and throw them into the mix: Water Weird, Water Elemental, Mudmen, certain Mephits, Kelpies, Gray Ooze, Sprites. It's a start - more to talk with needs to be added, a Water Naga, perhaps.
In addition to their level, I need to keep magic items in mind, especially the potion that can foul a large water source (also from d4 Caltrops), so I need to be careful about describing the lair - too much connectivity means the surrounding water sources are dead, and I can't have that. Although, that potion plus latent chaos magic tainting the area means all sorts of self-inflicted nastiness for the PCs.
I may even have to bust out the Monster Alphabet if Ford's Fairies doesn't have anything I can use. The Monster Manual is a last resort.
The last things I need are the lair map and keying it with monster and treasure locations. That and the remaining accessible treasure and the remaining buried-deep-in-mud treasure, itself. There will assuredly be enough overall for THE Group to reach level 5, because I want to see fireballs with cascading dice truly explode. More weird magic items - because they don't have enough already.
(That being another houserule, XP comes from GP acquired adventuring - I can already guess my next post).
So that is it, my thought process on designing 'an adventure' for my D&D game.
I hope it proves useful.