More On Backstabbing

A recent discussion of ways to play out the backstabbing mechanic has led me to review the rules, because they greatly influence the probabilities of success.  The Labyrinth Lord ruleset, as written, is extremely uncharitable to thieves in this one respect.  "[He] must catch an opponent unaware of his presense, using move silently and hide in shadows." The requirement to do both makes a successful backstab exceptionally improbable for low level thieves.  After a complaint from a player I've been trying to get interested in old school play, I've been exploring ways to adjust so that thieves could be a little more exciting to play.  Some of those ideas were discussed here.  I also decided to look it up in my old rule books.

According the Rules Cyclopedia:

If a thief can sneak up on a victim, completely unnoticed, the thief may backstab - if he is using a one-handed melee weapon, he may strike at particularly vulnerable points of his target's body. (Though the ability is called "backstabbing," the weapon doesn't have to be a stabbing weapon.  A thief can use this ability with a club, for example.)
...
If the intended victim sees, hears, or is warned of the thief's approach, the thief's attack is not a backstab; it is an ordinary attack, doing the damage appropriate for the weapon used.

When no battle is in progress, a backstab attack may require a Move Silently ability check.  The DM will make all the necessary decisions on that matter.

Furthermore, in my old, red box, Mentzer, D&D Player's Manual it describes the backstabbing ability this way:

If a thief can sneak up on a victim, completely unnoticed, the thief may Backstab.  If the intended victim sees, hears, or is otherwise warned of the thief's approach, a Backstab may not be taken but the thief may still attack normally.
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EXAMPLE: An Apprentice is carrying a sword, and sees an ogre approaching the party.  The player says "I'll Hide in Shadows."  The DM rolls 19 on d%, so the ogre does not see the thief (but the DM does not announce the fact). During the battle, the ogre gets turned around, with its back towards the thief.  The player says, "I'll try to move in for a Backstab!" The DM decides that the ogre doesn't notice the thief's approach (no roll is made; it depends on the situation, and the DM's judgement) and says "The ogre doesn't notice you; roll for a Backstab." The thief player then makes a Hit Roll...

So originally, the issue wasn't necessarily the game mechanics, but rather the DM's discretion. Depending on the situation, a DM might require a Move Silently check, a Hide in Shadows check, both, or none.  While I definitely am a big fan of the Labyrinth Lord rule set, I'm coming to appreciate it's differences from D&D.  In this one little respect, I think Labyrinth Lord desperately needs to be tweaked.  One of the brilliant features of old school gaming is how much is left to the dungeon master.  The way it's worded in Labyrinth Lord specifically, though, is excessively binding and needs to be house ruled. Otherwise, no rational player would backstab until achieving a fairly high level. Not only that, house ruling it would be more in keeping with the original game rules.

Backstabbing

In the course of a discussion of D&D tactics, it was brought up how in old school D&D the closest equivalent they have to "flanking" like in 3.5e is a thieve's backstabbing.  While I'm not sure the analogy is necessarily the best, it got me thinking about what the most effective use of backstabbing is.  For a thief to backstab, they have to use both their "Move Silently" and "Hide in Shadows" ability to move behind their target.  Because the probabilities multiply, a quick calculation reveals that this is a high-risk endeavor for any thief. Following the Labyrinth Lord rules, a first level thief has a less than 3% probability of successfully backstabbing, and no thief stands greater than 50-50 odds until he is 10th level.  Given that, my intuition is that the payoff for backstabbing is on average fairly low.  I'd only recommend thieves choose to backstab in the face of a real risk of total party kill (TPK).  To say more would require more modeling, though.  Since I'm already behind on my Markov model for my elf versus an orc, it's probably best that I hold off on going much further on this one.