Three Modules : Barrow of the Forgotten King / The Sinister Spire / Fortress of the Yuan-Ti
These three adventure modules flow together, taking PCs from 2nd through 8th level and will work great for a Ptolus Campaign. Explore catacombs beneath graves, an Underdark spire-city by a sunless sea, and storm a Yuan-ti castle to take the bones of a long dead king before an evil ritual is completed.