CAUTION: This series of articles contains many spoilers concerning the modules D1-3 and should only be read by DMs and those players who will not be actually playing through the series at any time in the future. Failure to observe this caution will lead to a marked lack of enjoyment in the adventures.
D3: The Vault of the Drow
Ah, the masterpiece. It gave us our first comprehensive look at the Drow, and was thus the inspiration for all the work that followed, Drizzt Do'Urden included. The pinnacle (or nadir, perhaps) of the work is the drow city Erelhei Cinlu, the ultimate inspiration for Ed Greenwood's creation Menzoberranzan. It is the last module in the series that Gary Gygax created, and found by many to be vastly superior to the final module in the series, Q1 Queen of the Demonweb Pits (although more about that later). Even the cover (of the monochrome version) is evocative; an evil High Priestess, curved dagger held aloft, is about to send a soul to Lolth (who is hovering overhead) atop a pile of skulls while a Mezzodaemon looks on. Priceless.
There are three minor encounters that lead to the city of the Drow, but in truth only one of them is really necessary to penetrate the capital of the dark elves, and surely if the party has by this time made allies of the subterranean dwellers here, they will know this. (Although it is interesting to note that on the players' map, the second encounter area does not exist; it merely shows a tertiary passage. Surprise!)
Speaking of the players' map, the glyphs that are marked thereupon should not be overlooked, especially as some of them repeat. The map itself is gained in module G3 Hall of the Fire Giant King, and if the PC's are clever in figuring out the clues, they will profit. Three of the are marked with eyes, similar to Egyptian hieroglyphics. The first one was a Drow checkpoint, manned by soldiers. The second is the major cavern in D1, which contains, well, a Drow checkpoint, manned by soldiers. Any guesses as to what the third one will contain? If nothing else, the PC's should put together the fact that there are Drow in the first two encounters, and expect to see them in the third. And encounter them they do.
The main path to the Drow city is a gatehouse, for want of a better word, manned by dozens of Drow soldiers. PC's which have figured out that infiltration tactics work best here will probably have some sort of plan already in place to get past such obstacles, posing as merchants, prisoners, allies, or somesuch. They might have some of the Drow clan emblems, and could bluff their way through the encounter. The DM should allow and even encourage such tactics on the part of the PC's! As I've stressed, it's the best (and perhaps only) way the party can conceivably succeed here. Needless to say, the DM must afford the party the chance to do so here. This is not a combat encounter unless the PC's want it to be! The Drow may very well be on alert for the party (depending on how they have comported themselves hitherto), in which case the sentries and their officers will afford them a much greater level of scrutiny than they otherwise might. A very paranoid group of PC's, seeing the Drow fortification, might even decide to split up and approach it hours apart, figuring the Drow would be looking for a group of eight, rather than two groups of four. The DM should absolutely reward such thinking.
The second encounter area is interesting because it is the only one that is not marked on the players' map. Silussa and her lover have set a bit of a trap for those who want to approach the Drow city via the less-used path. It's a fairly standard set-piece encounter, and one that could be theoretically transported into any setting or dungeon. But note that there is no explanation of the relationship of Silussa and Belgos and the regular Drow establishment; herein lies the path to greatness for a seemingly pedestrian encounter.
Do the Drow of Erelhei-Cinlu know of the cavern so close to their doorstep? How could they not? Why do they allow them to dwell here? Do they value their use as guardians of the "end run" around the standard gateway? Let us not forget that there are many factions within the Drow realm itself. Are Silussa and Belgos allied with the Eilservs faction or the Lolth faction? We know nothing, which leaves the DM free to answer those questions as they best serve his or her own campaign. Is Silussa a servant of Lolth? That could yield some very interesting possibilities, if she finds out that the party is there to thwart the ambitions of the Eilservs (rivals of the worshipers of Lolth, remember). And just what clan did Belgos belong to before he died? That could be vastly significant as well. Again, for the alert DM, there are many possibilities that could turn this seemingly-pedestrian encounter into one which drives the plot forward and is a potential source of either great aid or great hassle for the PC's.
The third encounter area really doesn't lend itself to a furtherance of the plot line, and seems to be included as another way that the PC's can find their resources taxed. Nasty spiders, and a potentially nasty treasure at the end. Given the geography of the map, if the players waste their time getting here, they deserve to get pummeled. It's a classic distraction/drain encounter, and the DM should milk it as such.
We now come to the Vault itself. One interesting note on the geography of the Vault; it is a dead-end, except for the river. No tunnels lead to it other than those stemming from the first (and second) encounter areas. It's a strategic cul-de-sac. I would infer that makes the river all the more valuable as a transportation artery from an economic point of view, and will have a bit to expand on that later. But perhaps it says something of the psychology or geopolitical calculations of the Drow that they would choose to locate their city in a place that was so inaccessible.
This is a module that really rewards a lot of prep work on the part of the DM. A full-blown city map of Erelhei-Cinlu would not be remiss. Bear in mind that the streets are regularly patrolled, but the back alleys are as dangerous as any dungeon. The place is more than a mile in length, and boasts a population of some 25,000 individuals, making it the equal or envy of many cities above ground.
Once the PC's arrive here, they are likely to encounter the inevitable question. "Why are we here?" The answer to that hinges on the question of whether or not they have figured out that only a single faction of the Drow was responsible for the deprivations of the giants, and whether or not they know which one it was. If they still think "the Drow are behind the giants, and we should stop them" then they have effectively declared war on the entire city. Wish them luck, and I hope they have 4d6 handy to roll up new characters.
Every encounter should reinforce the notion that the Drow are riven with division. That doesn't mean that there are allies on every side-- quite the reverse. The Drow version of the old saying could well be stated as "the enemy of my enemy is my tool." Every encounter with a bunch of rakes or a patrol of the Servants of Lolth should be a prime opportunity for the DM to have an NPC make a point of a clan pin pointing to inferior stock, or some ancient rivalry.
It should never be forgotten that the political situation among the Drow is not obvious. House Eilservs was behind the uprising of the giants, as a way of gaining power once their ambitions in the Vault were thwarted. Once the priestesses of Lolth turned against them, they in turn abandoned the worship of Lolth and took up that of the Elder Elemental God (more about whom can be found here).
That sets up a whole dynamic of rivalries, mixed in with religious animosities, which is explained in fair detail in D3. It must be stressed that the DM must give some opportunities for the PC's to get involved in those conflicts, as a way of resolving their own mission. Hiring on to the Eilservs is probably out of the question unless they do so through a third party (and wouldn't THAT be a difficult game to play-- almost more fun than rescuing a bunch of FARC hostages in Columbia), but not impossible.
One can hope that after a short time in the Vault the party will figure out that there is more than one faction amongst the Drow, and that they aren't all behind the giants' campaign on the surface. (Hopefully they will have picked up on enough of the DM's clues that they will have already figured that out before even getting to the Vault.) But even if they do, there are two possibilities that the DM must be prepared for:
1) "We need to stop the Eilservs once and for all, to halt their ambitions against the surface world"
2) "We need to stop the Drow once and for all, because they are evil and are ultimately a threat to the surface world."
The first attitude bears with it the implication that the Drow factions can be parleyed with, and used against other Drow factions. The second attitude implies that the party should be looking for some way to collapse the Vault itself. Think of all the x.p. from killing 25,000 Drow! (For the record, if any DM allows this to happen, he is entitled to a free cock-punch.)
The module, of course, implies the first option. If the PC's seriously contemplate the second, the DM should not forget that the Drow will mobilize against a threat to them all across all faction lines, and in such a case they should be dead in short order. The party can try the second, but unless the DM is being uncommonly generous, it should fail.
Which brings us to the whole question of Lolth's role in this module, and thus the role of Q1. Since Lolth's minions were never a part of the plot to incite the giants to action, it stands to reason that there would not be a reason to visit the Abyss to confront Lolth. If anything, the PC's should be Lolth's allies, at least in the limited sense of opposing the Eilservs. "The enemy of my enemy is my tool," so goes the saying...
I firmly believe that there is no reason to include a trip to the Abyss to confront Lolth. The PC's can achieve their goals (stopping the force behind the giants) by simply trashing the Eilservs and their allies. In fact, the adherents of Lolth might actually help them in doing so, since the Eilservs and the Lolth-worshippers are enemies within the Drow culture.
As DM you must play into all the politics, factionalism, and so forth that the module implies. At the same time, you must allow your players to use that to their advantage. Do so, and you and your players will have a grand time. All the political set-up in the world doesn't mean anything if the PC's can't make use of it.