RPG Horizon

How To Run The Thief

The thief class in Basic Dungeons & Dragons is a popular topic of discussion due to its unique mechanics, such as the use of percentile dice and the ability to backstab. But the specifics of these actions are not clearly defined. In order to provide a clearer understanding of these aspects of the thief class, we will need to rewrite some of the underlying system, without making major changes to the rules.


"Surprise" in D&D is a poorly explained mechanic related to stealth. This is evident in the fact that evasion automatically succeeds for a group that is surprised. This suggests that surprise is not necessarily the moment when opponents are caught off guard when you suddenly appear in front of them, but rather the opportunity to surprise them or the ability to leave without being noticed. To clarify this mechanic, we will rename it and adjust it slightly. Instead of rolling to determine if a character or monster is surprised, we will have them roll to determine if they have the opportunity to surprise others.

Encounters, Surprise, Surprise Checks

Each side rolls 1d6 to determine their stealth, lower is better. Most monsters and characters will be surprised by any side that rolls a 2 or lower. Some might be perceptive enough to require a roll of a 1.

If a group surprises another, they may act with a one round advantage (performing an action surprising to their foe, and then entering initiative as normal).

If a group has stealth, they may evade combat automatically.

Now we have revised the mechanic of surprise and renamed it "stealth." We have also kept the aspect of some monsters only being surprised on a roll of 1, as stated in their stat block.

To summarize, if a character's stealth roll is successful, they have stealth and can surprise others. Stealth is a passive ability, while surprising others is an active action that can be taken during a surprise round. Now it is time to rewrite the first part of the thief class.


Thief, Back-stab

When attacking a surprised opponent from behind, a thief receives a +4 bonus to hit and doubles any damage dealt.

We have made a small modification by replacing "unaware" with "surprised." With this change, a thief who has stealth can receive a backstab bonus when attacking during their surprise round. It is not necessary for the thief to physically stab the target from behind, as this adds unnecessary complexity to combat with miniatures.

This change provides clear guidance on when a thief can use the backstab ability: at the start of combat, if they have stealth and decide to surprise the opponent by attacking them after coming out of stealth.

Now that we have clarified the backstab ability, it is time to move on to the other skills of the thief class.

Climb sheer surfaces

While anyone can climb, thieves are able to climb sheer surfaces that would be difficult or impossible for others to traverse.

Find or remove treasure traps

The mechanics of this skill are explained well in Basic D&D. A thief can use it to locate and disarm traps on small objects such as locks. Other characters can assist in the search for traps in a room, but traps on treasure require the precise and steady hand of a thief.

Hear noise

In Basic D&D, there is a mechanic called "Listen at Door" which seems somewhat unusual. If this is treated as a general "listen" skill that all characters have, with humans having a 1-in-6 chance and demihumans having a 2-in-6 chance. The thief's "hear noise" skill can be treasted as an improvement on this, allowing them to start at the same level as demihumans and eventually surpass the listening skills of all other characters.

Hide in shadows

Everyone is able to hide, which is called stealth. It allows you to gain surprise. "Hide in Shadows" is the reason we introduced this mechanic. In general, time either moves in increments of 10 minutes or 1 day (in a dungeon or overworld) and it is not necessary to track the precise positions of characters at these scales. This allows us to have flexibility in positioning our thief.

This is useful when handling "Hide in Shadows" because it allows us to assume that the thief is always in the stealthiest position possible at the start of an encounter. If the party does not have stealth, the thief can use "Hide in Shadows" to gain an additional opportunity for stealth. This can be thought of as a saving throw to avoid being noticed by the enemy when an encounter begins. It gives the thief an additional chance to be in stealth and potentially use their backstab ability.

In addition, "Hide in Shadows" can be used during evasion and pursuit. If the thief is being chased and finds a place to hide while breaking line of sight, they can use "Hide in Shadows" to automatically evade (since they will gain stealth, which allows for automatic escape).

However, stealth does not have to be converted into a surprise round immediately. If the party and monsters start fighting and the thief remains perfectly still and silent, they will retain their stealth and can claim their surprise round between any two future rounds. This is useful in situations where the thief may want to wait for the party to engage before taking their surprise round, so that they are not the only person at risk of being attacked by enemy swords if the party loses initiative after the thief attacks in their surprise round.

Move silently

"Move Silently" allows the thief to reposition while maintaining stealth. They must not run across the line of sight of an enemy, but for simple repositioning without triggering a surprise round, they should make a "Move Silently" roll.

In addition, "Move Silently" can be used as a saving throw against an enemy's listen check. Just as characters have a general listen skill, monsters also have this ability, and any orc on watch overnight is likely using it. If the thief is with the rest of their party, it will not matter because the group will be heard regardless. However, if the thief is scouting ahead alone, a successful "Move Silently" roll will greatly improve their chances of remaining stealthy.

Open locks

One common complaint about the "Open Lock" skill is that low-level thieves are not very skilled at lockpicking. This may be because players view the chance of successfully picking a lock as the only factor in the process. To make thieves more effective at thievery, consider using locks of lower quality that grant a bonus to the pick success chance. Examples of this can be found in old BECMI modules, where locks are described as being of poor quality and granting a bonus to the pick chance. This will make the thief feel more successful in the game. While the lower lockpicking chance may not be a problem for some players, others may find it frustrating.

Pick pockets

The "Pick Pockets" skill allows a low-level thief to steal from someone's pockets without them noticing 20% of the time, which is a good success rate. People generally have good awareness of their personal belongings, especially in a pre-smartphone world where there are fewer distractions and crowded shoppers. The 60% chance of being noticed does decrease the effectiveness of this skill for the thief, but they can be more selective in who they try to steal from to mitigate this risk. The goal of the game is often to acquire gold, and pickpocketing wealthy individuals is a quick way for the thief to do so.

In this article, we discussed all of the thief skills and how they can be used in gameplay. The most important parts are the discussion of "Hide in Shadows" and "Move Silently" in relation to stealth and surprise in combat. These rules are not meant to replace any out-of-combat or more general use of these abilities, but rather to provide useful default procedures that make the thief class feel more effective and true to its theme.

Author: Lucille L. Blumire

Published: Sun, 27 Sep 2020 14:09:00 GMT

Original: How I run the thief. Old-school musings on the thief class.