D2, and D3 are 9019, 9020, and 9021 respectively (9021 being reused for the new Erol Otus cover with the blue background). Reception When combined with the G-series and Q module as the Queen of the Spiders, the D-series was voted the single greatest adventure of all time by Dungeon magazine in 2004. Reviewer Alan Kohler said, "The Underdark has become a classic place to set adventures... This is where it all got started." According to the editors, Vault of the Drow would have made the top five if it had been considered as a single module. They felt the Drow city detailed in the module offered "more intrigue" than any module previously. Judge Clark Peterson compared it favorably to City State of the Invincible Overlord, which also had a complicated city environment, saying "this was an underground city of evil monsters—the Drow, who, then, were new and mysterious as opposed to tired and overused as they are today." Dungeon Master for Dummies lists Descent into the Depths of the Earth as one of the ten best classic adventures, noting that it takes "the player characters into the underground world of the Drow—the wildly popular dark elves of D&D lore." The series has received considerable praise. It was reviewed by Don Turnbull in British RPG magazine White Dwarf No. 11, who gave it 10 out of 10. He compared the series favorably to the G series of modules, which he also liked. Turnbull commented that the scope was large, and that the modules were of good value. Although D3 can be played by itself, he speculated that the party of characters may need the magic items that can be acquired in the first two to not be put at a disadvantage. Turnbull did lament that the series was designed for parties of a high level, making it difficult to use with a group of lower level characters. He concluded the review by saying "don't be surprised if they eclipse in quality most of the material you already have." All three modules are also profiled in Heroic Worlds, Lawrence Schick's 1991 guide to role-playing games. The D-series of modules was also given an extensive overview review by Turnbull in issue No. 15 of White Dwarf, wherein he cautioned DMs that running these modules was unlike any they had run before. He commented that the adventure would be too difficult for most