While I like the method presented in Call of Cthulhu for reading occult grimoires, it doesn’t lend itself easily to wholesale incorporation into D&D, something that the D20 version of CoC had to wrestle with. Rather than use the D20 method, which isn’t very OD&D friendly anyway, I’ve been cobbling together a system that somewhat simulates the dangers of the ineffable grimoires of CoC, yet is still rooted deeply enough in D&D. I think I’ve found a solution.
Taking a hint from Expedition to Barrier Peaks and Gamma World, I landed on using a flowchart to simulate the process of deciphering occult tomes. While I wouldn’t use this method for run-of-the-mill spellbooks and the pre-existing magical books in the game, it’d work well if I wanted to drop my own version of Al-Azif into my campaign world. I’ve presented a rough cut of it below.
Deciphering Strange Tomes
Step One: The PC attempting the read the text must either know the language it is written in or possess suitable magics to translate it (read magic, read languages, helm of comprehend languages and read magic, etc.). Additionally, the text must be suitable to the PC’s class (arcane texts for MU and Elves, religious tomes for Clerics).
Step Two: The referee determines how long the character must read the book before a D10 roll is allowed on the chart below. Shorter texts may allow the PC to roll on the chart once per day, medium-length texts might require three days in between rolls, and dense tomes might require a full week to pass before a new roll is allowed. During each increment of reading, the PC may not adventure or conduct any other actions other than attending to his or her basic needs. Any interruption of the PC’s perusal of the text requires to character to start the current reading period anew.
Step Three: After the appropriate passage of time, the PC rolls a D10 modified by his INT or WIS score (see below) depending on his class and the adjusted total is applied to the flowchart to determine the character’s progress in his reading comprehension and the effects (if any) that occur as a result.
Reading Comprehension Modifier
INT or WIS of 9-12 – no adjustment
INT or WIS of 13-15 – minus 1 to roll
INT or WIS of 16-17 – minus 2 to roll
INT or WIS of 18 – minus 3 to roll
Step Four: Once the modified D10 roll is determined, the referee consults the chart above to determine the character’s progress. If movement along the flowchart results in anything other than one of the empty circles, an unforeseen effects occurs as a result of the PC delving into forbidden mysteries. Based on the PC’s current location on the flowchart above, roll the appropriate die on the table below apply the effect. If the referee chooses, the character may make a save vs. spells to avoid the effect.
1 – Reader ages 1d4 years.
2 – Reader develops the compulsion to drink ink once per day.
3 – Reader develops bibliomania and will go to extreme lengths to acquire new reading materials.
4 – Reader begins to speak in tongues and is incomprehensible without the use of magic.
5 – Reader is struck illiterate.
6 – Reader is afflicted by a geas to finish the book.
1 – Reader’s hair turns white or falls out.
2 – Reader’s fingers & tongue are permanently stained black.
3 – Reader becomes near-sighted (-2 to ranged attacks).
4 – Reader has an insight about the book (-1 modifier to future Reading Comprehension rolls)
5 – Reader experiences vivid hallucinations of non-Euclidean cityscapes.
6 – Reader develops an odd habit or behavior (facial tic, nervous fidgeting, odious personal habit, etc.)
1 –Reader is permanently blinded.
2 – Reader is struck feebleminded.
3 – Reader suffers a stroke and becomes completely paralyzed on one side of his body.
4 – Reader’ soul is snared by the book (as the spell, Trap the Soul).
5 – Lose 1d3 points of INT or WIS (depending on class).
6 – Reader turns to stone.
1 – Reader suffers violent nightmares (no natural healing or memorization of spells allowed).
2 – Eyes turn an unnatural hue (lose 1 point of Charisma).
3 – Reader uncontrollably broadcasts his thoughts to all creatures within 60’ (as ESP).
4 – Reader gains either the ability to use infravision (as the spell) or x-ray vision (as the ring) once per week.
5 – Reader learns 1 new language regardless of INT score.
6 – Reader gains the ability to read language (as the spell) once per week.
1 – Reader loses 1 point of WIS and gains 1 point of INT (or vice versa).
2 – Reader gains deeper understanding of the universe (may ask three questions as per Contact Other Plane).
3 – Reader suffers an alignment change.
4 – Reader makes a new discovery (learns new magical item construction method, learns a command word, discovers a power being’s true name, etc.)
5 – Reader gains 3d6x100 experience points.
6 – An invisible stalker appears to slay the reader.
Note: Any time a strange event occurs, the reader realizes that he is failing to grasp the contents of the text as intended or has otherwise drawn false conclusions about the book’s subject. He must start the research process anew in order to fully comprehend the work.
Skull & Crossbones
Character either goes permanently insane or must save vs. death or perish (50/50 chance). If character must save vs. death, a successful save still results in the loss of 1d3 points of both INT and WIS.
Step Five: Once the” Finish” circle is achieved, the tome reveals its full contents to the reader (new spells, magical formulae, sinister knowledge, advancement in level, etc.). Although the reader is never compelled to complete his study of the tome (unless geased as a result of his readings – see above) and may put the book down at any time, only by reaching this final spot on the flowchart may he make use of its contents.
There are a few rough edges that need filing down, but the premise strikes me as the correct avenue to pursue. I'll tinker a bit more when time allows.