Caverns of Thracia is a legendary “megadungeon” originally for OD&D.
A 3.5 conversion does not exist as an official WotC product. Instead, you’ll find:
✅ Most helpful: Look for the d20 version by Necromancer Games (published 2005-ish). It is fully 3.5-compatible and the closest you’ll get to an official PDF.
While no official Caverns of Thracia 3.5 PDF exists, a fan conversion circulates online, updating the classic dungeon to 3.5 rules. It preserves the legendary mapping and exploration style while rebalancing encounters for the d20 system. DMs seeking old-school challenge with modern mechanics can adapt the original Judges Guild PDF using a conversion guide or find a fan-produced file with caution regarding copyright. caverns of thracia 3.5 pdf
Note: I cannot provide direct links to or copies of the PDF, as that may violate copyright. However, the original Caverns of Thracia (non-3.5) is legally available for purchase as a PDF and can be manually converted using the 3.5 Conversion Manual or similar resources.
Would you like assistance writing a conversion guide instead, or a detailed encounter example for 3.5? Fan conversions (PDFs/Docs) – stat blocks, skill DCs,
Every guard, ghoul, and gorgon has been re-statted with feats, skills, and attack bonuses consistent with the 3.5 Monster Manual. No more guessing what a "Herd Animal (Aurochs)" AC translates to.
If you only have the OD&D version, here’s how to convert on the fly: ✅ Most helpful : Look for the d20
| OD&D / Basic | D&D 3.5 | |---------------|----------| | AC (descending) | 20 – listed AC = ascending AC | | Hit Dice | Keep HD; add CON mod for important monsters | | Saving throws | Use Fort/Ref/Will by monster type (e.g., humanoid: good Ref) | | Treasure XP | Ignore; use 3.5 CR-based XP | | Traps | Convert to Search DC ~20–25, Disable Device DC ~20–30 |
Example:
3.5 combat is more tactical than AD&D. The PDF updates monster intelligence scores. Use this: