Read Languages

Out of necessity, thieves tend to learn odd bits of information. Among these is the ability to read various languages, particularly as they apply to treasure maps, deeds, secret notes, and the like. At 4th level, the Thief has enough exposure to languages that he has a chance to read most non-magical writing. This ability naturally improves with more experience. However, your DM can rule that some languages (those the thief has never encountered) are indecipherable to the thief.

The die roll to read a language must be made every time the character tries to read a document (not just once per language). A successful die roll means the thief puzzled out the meaning of the writing. His understanding of the document is roughly equal to his percentage chance for success: a 20% chance means that, if the thief understands it at all, he gets about 20% of the meaning. A different document in the same language requires another die roll (it probably contains different words). It isn't necessary to keep notes about what languages the thief has read in the past, since each document is handled individually.

Only one die roll can be made for any particular document at a given experience level. If the die roll fails, the thief can try again after gaining a new experience level.

If the character knows how to read a given language because he spent a proficiency slot on it, this die roll is unnecessary for documents in that language.