Originally posted here: https://theotherside.timsbrannan.com/2020/11/classic-adventures-revisited-s4-lost.html
One of my all-time favorite adventures is S4 The Lost Caverns of Tsojcanth.
A solid two-level dungeon crawl, filled with new monsters, dangers, and the promise of great treasures. Additionally, there are rumors of an ancient witch/archmage and her battles with demons and even the threat that some of those demons are still around. There is plenty of wilderness area as well. A wide expanse with a gnome community nearby and a raging blue dragon.
With its "Booklet 2" filled with new spells, magic circles, and demons it made me think that a witch class with ritual magic could be something that would work for D&D.
There is so much great stuff in and around this adventure it is hard to know where to begin. So let's start with the adventure itself.
S4 The Lost Caverns of Tsojcanth
The adventure, S4 The Lost Caverns of Tsojcanth, was published back in 1982 by TSR. It was written by none other than Gary Gygax himself. It is listed as "S4" and was the last of the labeled "S series" or Special modules. This includes some of the most popular adventures ever written; S1 Tomb of Horrors, S2 White Plume Mountain, and S3 Expedition to the Barrier Peaks.
The adventure itself is comprised of two 32 page booklets. The first book is the adventure itself, which I will get into detail in a bit. The second booklet covers all sorts of new magic, monsters, and more.
Book 1: The Adventure
The adventure is of the classic sort; the rumor of treasure and a vague threat coming from an area of the map known as Iggwilv's Horn. The adventure is designed for characters level 6 to 10. I have found over the last 40 years that it can be adapted to a variety of levels, though higher levels are better. Though the original tournament adventure featured slightly lower levels. Likely due to the addition of the wilderness adventure.
The wilderness adventure is actually well put together and not the older crazy random monster encounters. The encounters make sense for the area. Among the encounters are the Hermit, and I could not help make this the same hermit from Keep on the Borderlands (also a Gygax creation) and the Blue Dragon. The Blue Dragon, in particular, became so much a hit the first time I ran this that in future runnings of this I changed the dragon to Korbundar from CM2 Death's Ride to have a reoccurring villain. A lot of adventure is packed into 12 pages.
The second part of the adventure covers the Lost Caverns themselves, which includes the Lesser and Greater caverns. This features a large variety of new monsters, some living here, some just wandering around. Even encounters such as "The Garden of One Thousand Earthly Delights" have a good (enough) reason to be there.
The final encounter is in the center of the Greater Caverns and it is not for Iggwilv's Treasure, but rather against Iggwilv's Treasure; the vampire Drelnza. She is a bit more powerful than your average vampire and she has magic to help her out. Eventually, she will succumb to heroes and the treasure will be found including the infamous Demonomicon of Iggwilv, Daoud's Wonderous Lanthorn, and the Prison of Zagig.
Book 2: Monsters and Magic
This second booklet, as I have mentioned, grabbed my attention as much as the first, if not more. Listed inside were new monsters, only some appeared in the adventure, including new demons and demon lords. There were the mysterious Xag-ya and Xeg-yi, the Derro and the awkwardly named (for the early 80s) Valley Elf. All these creatures would later be reprinted in the Monster Manual II for 1st Edition. This is fitting since the original tournament adventure introduced monsters that would become part of the first Monster Manual. There are some magic items including some wonderful artifacts mentioned above. Of these The Demonomicon of Iggwilv capture not just my imagination, but that of hundreds of others. The Demonomicon became a feature in Dragon Magazine and even a 4e book of the same name. Iggwilv went from a "long-dead archmage" to "The Mother of Witches" and the premiere demonologist in D&D. This little booklet also contains plenty of new spells.
This was classic AD&D at the end of it's 1st Golden Age.
The adventure is extremely playable and I have adapted it over the years for AD&D 2nd ed, D&D 3rd, and 5th Editions as well.