The Vault of Evil Opened (1998)

From the introduction:

This adventure is designed for 4-6 good-aligned characters of 6th to 9th level and is intended to introduce a new villain (Melengar) and a powerful evil artifact (the Rod of Ruin) into an ongoing campaign. As written, the PCs are not expected to encounter Melengar or the Rod of Ruin during the course of this adventure; rather, after completing this module, the PCs should be aware of the fact that some evil being has recovered an ancient and dangerous artifact. How much information the PCs learn of Melengar and the history of the Rod of Ruin during the course of this adventure is left to the DM, leaving open the opportunity for several follow-up adventures as the PCs try to gather information concerning their new foe and the artifact, eventually culminating in an epic assault on Melengar's labyrinthine catacombs. If, however, the DM wishes to run this adventure as a stand-alone module, then Melengar could be reduced in level, and the powers of the Rod adjusted to match the level and abilities of the PCs. If the DM chooses this approach, a suggested alternate ending is detailed at the end of the module.

User summary:

This item typically is distributed as a ZIP archive including the adventure document and two GIF image files (maps).