So now that we have a general plot and backstory for our dungeon, we are in the best position to create a good hook for the PCs to enter the fray.
Assume that the PCs begin the adventure in a small village or town that happens to be in the crossfire of the impending war between orc tribes. A powerful orc chieftain has put a price on the head of another one. The upcoming battle can be between those two orcs or the orc with the price and another who intends to collect the bounty. It doesn’t really matter, and it may never depending on how the PCs play this adventure.
The important thing is that the PCs are located in a population center that is about to be trampled by orcs, and that should give them incentive to do something about it.
Let’s take a brief side trek into the idea of railroading the PCs. No one likes to be forced into playing a specific way, or (as the Knights of the Dinner Table put it) “run over by the plotwagon.” But that doesn’t mean there is nothing you can do to ensure that your precious dungeon will be explored.
You hope that the PCs will trek into the jungle ruins to obtain a rare spell component needed by the wizard Gerhardt to banish all orc combatants to the plane of Acheron, where they will be just one battle among millions. That isn’t the only way to solve this crisis. Another way, for example, would be to use diplomacy on the orcs. And as a DM, I wouldn’t stop the PCs from trying.
Instead, deny them admittance to either camp (even under the flag of truce). The orcs aren’t interested in receiving ambassadors and the war will go on as planned.
Or, allow them to negotiate but have the negotiations break down. When the PCs describe doing something ordinary (like setting a weapon out of immediate reach to signal peace) declare it an affront to this particular orc tribe. Now the bounty on the opposing orc chieftain doubles!
If they learn of the bounty on the orc’s head, they might attempt to collect it themselves. Again, I wouldn’t try to stop them. However, I would attempt to dissuade them from this folly by describing the sheer size of the orc camp and the myriad orcs that inhabit it. Spend a moment describing the keen blades they carry, the glint of the sunlight off their spears, and the dull armor they wear splattered with the blood of many foes.
If a group of four PCs want take that on, then may Pelor be with them.
Of course, most gaming groups will ultimately opt for the most bloodshed and destruction possible, and want to face the orcs head-on. You should discourage this in much the same way as the previous point.
The only real path open should be what the wizard Gerhardt suggests: a foray to an ancient temple nearby known to house the rare spell component. But it won’t be as easy as we hope. A small cult of yuan-ti have taken over this temple and made it their own.
The first encounter is the guardian. There should be some difficulty getting into the dungeon. Psychologically, if the PCs feel like they conquered something to get in here, they will be more invested in staying with it. They didn’t just fall into this; they fought into this!
It doesn’t have to involve combat. Think of The Fellowship of the Ring. The tentacled beast from the water only kept the Fellowship in the dungeon. To open the stone doors, they had to solve a riddle. It was so simple it was hard: “Speak, Friend, and Enter.” They needed to speak the Elvish word for friend, but that wasn’t obvious from the outset.
The best rule of thumb to keep in mind is that the longer the dungeon has been unexplored, the tougher the guardian or more complex the ritual to unlock the door. If it was easy to get in, then the dungeon would have been raided long ago.
Consider the old Dungeon magazine adventure “The Whispering Cairn” (Dungeon #124, July 2005). The PCs enter a cave and battle a wolf and her cubs. Then they move into a grand tomb of one of the Wind Dukes of Aaqa, which lays unguarded. If the PCs try to search for treasure, they find that it has been looted long ago. Why? Nothing prevents the looting.
But, if the PCs explore further, they find a complex puzzle. Everburning lanterns, in each of the colors of the rainbow, hang in several passages radially arranged around the tomb. Three are missing; one was found in a backpack in the wolves’ den. The other two are recoverable in the builder’s caves, located behind a hidden entrance in one of the passageways. If the PCs recover the missing lanterns and put them in the right places, a new passageway opens up and leads to the true tomb of the fallen Wind Duke. This new tomb has all the loot in tact because no one yet figured out the complex puzzle in the false tomb.
In our scenario, we don’t need a complex riddle. This cult has set up here recently, perhaps a few months to a year ago, and the ruins aren’t visited often by the locals anyway. We can, therefore, justify using a pair of low-level yuan-ti as guards.
Yuan-ti are CR 3, 5, or 7 creatures depending on the subtype. This suggests a party level of 3-5 for this adventure. I want to challenge them without killing them, so a pair of purebloods just outside the temple should do it.
For the temple itself, try this battlemat. It’s not in production anymore, but it might still be available on eBay. A small section is, very crudely, printed below with combatants positioned. The PCs should approach from the bottom.
The PCs will, for the first time, realize that there is more going on here. Yuan-ti aren’t loners. They set up cities, much as humans do. You may allow for a DC 10 Knowledge (nature) check to reveal this information to them if they don’t already know, so they understand the gravity of their predicament. This now sets the stage for future encounters with yuan-ti.
Creatures (EL 5): The purebloods will make for a Very Difficult encounter for parties of 3rd or 4th level, and it will be Challenging for characters of 5th level. This encounter should challenge the PCs to the full, but not kill them. Psychologically, if your players had to work hard to get into the dungeon, they will want to explore it. It will feel like they earned the right.
Yuan-ti purebloods (2): hp 20, 21; Monster Manual 263.
Tactics: As the PCs approach, the yuan-ti order them to stop in Common. Then, both try to use cause fear before ordering the PCs off their sacred land.
If the PCs refuse or if the cause fear spell-like ability fails, the yuan-ti will attack. One will move to engage as many PCs as possible close to the treeline while the other one will use entangle to grab the PCs in the trees and weeds. That causes the area of effect to count as Difficult Terrain and trapped PCs to must make a DC 20 Escape Artist check (a full-round action) to break free.
They switch places and use the other tree line for a similar tactic.
While the PCs are busy with the flora, the yuan-ti pelt them with arrows. Once they run out of arrows or the PCs escape, the yuan-ti engage in straight melee combat using their masterwork scimitars.
Development: The yuan-ti fight to the death to protect their brood, however they aren’t stupid or reckless. Both break combat and run if reduced to 10 hp or less. If one makes it to the top of the stairs, she yells down to the other yuan-ti below. Three more purebloods led by a halfblood (see Monster Manual 264) arrive 1d6+1 rounds after the call for help.
When designing specific encounters, remember that you will have many, many more encounters than 5. The main plot is likely to be supplemented with one or more subplots. The main 5 encounters, however, should all tie back to the theme (Room 0) that we discussed earlier. This means all of these encounters will have something to do with yuan-ti, snakes, or the rare spell component we’re after.
So we have a hook and we have a guardian at the threshold. Not a bad start for our little adventure. Once the PCs gain entry to the dungeon itself, the real fun begins.