Significant Error

The Jovial Priest noticed an odd comment in a review of the AD&D Wilderness Survival Guide: "WSG gets proficiency checks right, correcting a major DSG error". He didn't see what was so bad about the way DSG proficiency checks work, compared to how WSG proficiency checks work. I didn't see the problem, either, until I went back to the books today to figure it out.

In both the DSG and the WSG, proficiency checks are ability checks; in other words, you roll a d20 and are successful if the roll is lower than the ability score that governs that action.

In both, there is an automatic failure range for the check. In both, proficiencies apply modifiers to the check. In both, the modifiers become larger when the players spends a proficiency slot to improve a non-weapon proficiency. But in all three of these cases, the specifics for DSG proficiency checks are quite different than the WSG.

• Automatic Failure: WSG= 19-20. DSG= 1-3.
• Modifiers: WSG= TN+modifier (success more likely.) DSG= d20+modifier (success less likely.)
• Proficiency Slots: DSG= add +2 to roll per extra slot (higher proficiency = success less likely.)

In other words, the DSG is backwards. I never noticed this back in the day. Here's a relevant quote from the DSG: "The player rolls 1d20 and compares the result to the character’s ability score in the area listed for that proficiency. In many cases, a proficiency will be listed with an Ability Check modifier (see the specific proficiencies). This is a die roll modifier. Thus, a +3 makes a d20 roll of 12 equal to a 15. In addition, as a character uses additional proficiency slots to improve a given proficiency (instead of adding a new one), the proficiency die roll modifier is increased by 2 for each additional slot" (Emphasis added.)